A Samsung Galaxy A21s screen replacement means fitting a new 6.5-inch LCD display assembly to the phone's frame and reconnecting it to the motherboard through the LCD flex cable. It is one of the more approachable Samsung screen repairs, because the A21s has a plastic back that is easier to remove than glass, but you still need heat, patience and the right adhesive. At E-Tech61, the A21s (SM-A217) screen replacement costs £40.00 and the main board to LCD flex cable costs £4.89 (prices checked 15 October 2026). Before ordering, check whether the fault is the screen itself or the flex cable that connects it, because a damaged flex can cause a black screen, lines or flicker on a perfectly good display. This guide covers diagnosis, parts, tools and the full replacement process.
Galaxy A21s screen basics
Samsung released the Galaxy A21s in 2020 as a budget phone with a 6.5-inch HD+ LCD display with a punch-hole front camera, a large 5,000mAh battery and a rear fingerprint sensor, as listed on the Galaxy A21s entry on Wikipedia. Because the display is an LCD rather than an AMOLED panel, replacement screens are less expensive than on Samsung's flagship models, and the fingerprint sensor is on the back, so it is not affected by a screen swap.
The UK model number is SM-A217F. Check it in Settings > About phone before you order, because the A21s screen is different from the A21 (without the "s"), the A20s and other similar-looking models. The wider Galaxy A range is summarised in the Galaxy A series overview.
Is it the screen or the flex cable?
The A21s display connects to the motherboard through a separate main board to LCD flex cable. That cable can be damaged by a drop, by liquid or during a previous repair. Use these symptoms to narrow it down:
- Cracked glass, black blotches or spreading ink marks: the screen is damaged. Replace the screen.
- Coloured or white lines with no visible crack: could be either the screen or the flex. Reseat the connectors first, then test.
- Black screen but the phone rings or vibrates: could be the screen, the flex or the board. Test with a known good screen if possible.
- Flickering that changes when you press near the bottom of the phone or flex the body: often points to the flex cable or a loose connector.
- Touch not working, display fine: usually the screen assembly (the touch layer is part of it) or its connector.
Repair shops should test with a known good screen before replacing anything. If a good screen works perfectly, the old screen was faulty. If a good screen shows the same fault, replace the flex cable or investigate the board.
How to fix a Samsung A21s black screen
Before buying parts for a black screen, rule out simple causes:
- Force restart: hold Volume Down and the Power key together for at least seven seconds until the phone restarts.
- Charge it: plug in a known good charger and cable for 30 minutes. A completely flat battery can look like a dead screen.
- Check for signs of life: if the phone vibrates, rings or connects to a computer, the phone is running and the display path is the likely fault.
- Torch test: shine a bright torch at an angle onto the screen. If you can faintly see icons, the LCD is working but the backlight is not, which usually means a damaged screen or a board-level backlight fault.
- Check for liquid damage: liquid can corrode the display connector. Cleaning connectors with isopropyl alcohol sometimes restores the display.
If none of these help and the phone is clearly running, replace the screen or, if a good screen also stays black, the flex cable.
Parts and tools you need
- Replacement screen for the A21s (SM-A217).
- LCD flex cable if diagnosis points to it, or if the existing one was damaged during disassembly.
- Heat source: heat mat, heat gun on a low setting or a hair dryer.
- Opening tools: suction cup, plastic picks, plastic spudger and an opening card.
- Phillips #00 screwdriver and a magnetic screw mat.
- Adhesive: screen adhesive tape or a flexible black adhesive such as T7000, plus adhesive for the back cover.
- Isopropyl alcohol for cleaning old adhesive.
Browse our repair tools and adhesives.
How to replace a Samsung A21s screen: step by step
These steps describe the general process. For model-specific photos, the iFixit Galaxy A21s repair page is a helpful companion. Read all steps before starting.
1. Prepare
Back up the phone if possible. Discharge the battery below 25%, power off and remove the SIM tray.
2. Remove the back cover
Warm the back cover gently to soften the adhesive. Insert a pick at the bottom edge and work around the sides, releasing the clips and adhesive. The back cover is plastic, so take care not to bend or crease it. Note the fingerprint sensor flex if it is attached to the cover, and disconnect it carefully before removing the cover fully.
3. Remove the midframe covers
Unscrew the plastic covers over the motherboard and the bottom board. Keep screws in order.
4. Disconnect the battery
Lift the battery connector with a plastic spudger before touching any other connectors.
5. Disconnect the display flex
Disconnect the LCD flex cable from the motherboard. Inspect it and the connector for tears, burns or corrosion. If it looks damaged, replace it during this repair.
6. Remove the broken screen
Heat the front of the phone evenly around the edges. Use a suction cup and picks to lift the screen away from the frame, working slowly around all sides. If the glass is badly shattered, cover it with packing tape first to hold fragments together, and wear eye protection. Feed the screen's flex cable out through the slot in the frame as you lift it away.
7. Clean the frame
Remove all old adhesive and glass fragments from the frame with a plastic tool and isopropyl alcohol. A clean, flat frame is essential for the new screen to sit flush.
8. Test the new screen
Feed the new screen's flex through the frame, connect it, reconnect the battery and power on. Check display brightness, colours, touch across the whole screen, the front camera through the punch hole, and the earpiece and proximity sensor. Power off and disconnect the battery again once testing is complete.
9. Bond the new screen
Apply adhesive tape around the frame edge, or a thin, even bead of flexible black adhesive. Remove protective films from the inside of the new screen, align it carefully and press it into place. Clamp gently or place light weight on it while the adhesive cures according to the product instructions.
10. Reassemble
Reconnect the display flex and battery, refit the midframe covers and screws, reconnect the fingerprint sensor, and refit the back cover with fresh adhesive. Power on and run a final test.
Screen tape or liquid adhesive?
Both work on the A21s, and repairers have their own preferences:
- Pre-cut or roll adhesive tape gives a clean, even bond with no mess and allows the screen to be removed more easily in future. It needs a perfectly clean frame, and it can be fiddly to position along narrow edges.
- Flexible liquid adhesive, such as T7000 black glue, fills small gaps in a slightly uneven frame and blocks light from leaking at the edges. It needs a steady hand, a thin bead and time to cure under light clamping. Too much glue is the most common mistake.
Whichever you use, avoid covering the earpiece grille, the proximity and light sensor area at the top of the screen, and the microphone hole. Wipe away any squeeze-out with a cotton bud before it sets.
After the repair: settings and checks
Once the phone is back together, run through a short checklist. Adjust brightness from minimum to maximum and check auto-brightness responds when you cover the top of the phone. Make a test call and cover the top of the screen to check the proximity sensor turns the display off. Use the front camera to make sure nothing is blocking the punch hole. Finally, leave the phone face down under light pressure for a while if you used liquid adhesive, and ask the customer to avoid pressing hard on the screen edges for the first day while the bond reaches full strength.
A21s screen replacement cost
As a DIY repair, the main costs are the screen (£40.00 at E-Tech61) and, if needed, the LCD flex cable (£4.89), both checked 15 October 2026, plus adhesive and tools if you do not already have them. A repair shop will add labour, which varies by location. For an older budget phone, compare the total with the phone's value; if the battery is also tired, factor that in too. See our screen replacement cost guide for wider context.
Common mistakes
- Ordering the wrong model. A21, A21s and A20s screens differ. Check SM-A217F.
- Not disconnecting the battery first. This risks damaging the new screen or the board.
- Too much heat. Overheating can damage the LCD, the plastic back cover and the battery.
- Too much glue. Excess adhesive can seep onto the display or into the earpiece and sensors.
- Skipping the test. Always test before bonding the screen permanently.
- Forgetting the protective films. Remove films on the inside of the new screen before bonding, and the outer film only once finished.
- Pinching the flex. Route the display flex through the frame slot carefully so it is not trapped when the screen is pressed down.
Tips for repair shops
The A21s is a common budget phone, so stocking screens and LCD flex cables saves waiting time. Agree the repair and price with the customer before starting, note any existing damage to the frame or back cover, and explain that water and dust resistance should not be assumed after a repair. For other Samsung models, browse our Samsung Galaxy A series parts and the full Samsung parts range. All A21s parts are in the Galaxy A21s A217F parts collection.
Recycling the old screen
Broken screens and phone parts should go to a WEEE recycling point, not household rubbish. Recycle Your Electricals has a postcode search for local drop-off points.
Frequently asked questions
How do I replace a Samsung A21s screen?
Remove the back cover, disconnect the battery and display flex, heat and remove the old screen from the front, clean the frame, test the new screen, bond it with adhesive and reassemble.
How much is a Samsung A21s screen replacement?
The screen costs £40.00 at E-Tech61 (checked 15 October 2026). A repair shop will add labour.
How do I fix a Samsung A21s black screen?
Force restart (Volume Down and Power for seven seconds), charge with a known good charger, and use the torch test. If the phone is running but the display stays dark, replace the screen or the LCD flex cable.
Does the A21s screen replacement affect the fingerprint sensor?
No. The A21s fingerprint sensor is on the back, not under the screen. Just remember to reconnect its flex when refitting the back cover.
Can I replace just the glass on an A21s?
Not practically. The glass, touch layer and LCD are bonded into one assembly, so the whole screen is replaced.
Is the A21s screen LCD or AMOLED?
It is an LCD (PLS TFT type) display, which is one reason replacement screens are less expensive than on Samsung's AMOLED models.
How long does an A21s screen replacement take?
An experienced technician can usually complete it in under an hour, plus adhesive curing time. A first-time DIYer should allow two hours or more and should not rush the screen removal or cleaning steps.
Next step
Confirm your model is SM-A217F, diagnose whether the screen or the flex cable is at fault, then order the parts you need from the buy boxes above along with adhesive and tools. Parts ship from E-Tech61 in the UK.
Share:
Redmi Note 8 Broken Screen: Replacement Guide