Power Button Flex Cable
Samsung Galaxy S21 Power Button Flex Cable Replacement
- Fits
- Samsung Galaxy S21
- Fixes
- Unresponsive power button
- Quality
- Brand new, OEM quality
- Fitting
- Professional install
Overview
What this part is
On the Galaxy S21, the side (power) button presses onto a thin flex cable inside the frame. After a drop, liquid damage or long use, the switch on that flex can wear out or tear, and the button stops responding.
A new flex cable restores the click and response. If the plastic or metal button cap on the outside is bent or missing, check that as well.
Compatibility
Specifications and compatibility
- Part
- Power Button Flex Cable
- Compatible with
- Samsung Galaxy S21
- Model numbers
- SM-G991B
- Does not fit
- Galaxy S21+, S21 Ultra or S21 FE
- Fixes
- An unresponsive, sticky or intermittent power button caused by a worn or damaged flex
- Does not fix
- A bent or missing outer button cap, software faults or motherboard faults
- Quality
- Brand new, OEM-quality power Button Flex Cable. Tested before dispatch.
- Brand
- Unbranded, compatible with Samsung Galaxy S21
- In the box
- 1 × power button flex cable. Check the photos for any extra items.
- Colour
- As shown in the photos
- Installation
- Professional installation recommended
- Supplied by
- Supreme Phone Parts Ltd, Manchester, UK
Before you order
Is this the right part?
Signs it needs replacing
- The side button does nothing when pressed
- You have to press very hard for the button to work
- The button works only some of the time
- The phone restarts or locks by itself
How to check your model
Open Settings › About phone. The name should read Galaxy S21 and the model number should be SM-G991B (UK models start SM-). Compare your old part with the photos before fitting.
Professional installation
How a technician fits this part
- Power the phone off and remove the SIM tray.
- Warm the back glass edges and lift it off carefully with a thin pick.
- Remove the screws and the inner cover over the main board, then disconnect the battery.
- Unplug the old power button flex, peel it from the frame and fit the new one in the same position.
- Reconnect the battery and test the side button before closing.
- Refit the inner cover and screws, apply new back adhesive and press the back glass on evenly.
Check that the part matches the device before fitting it or removing any adhesive backing. Once a part has been fitted, it cannot be returned for a change of mind. Faulty parts are always covered.
FAQ
Frequently asked questions
Will this fit my S21?
Yes, if Settings › About phone shows Samsung Galaxy S21 (SM-G991B). It does not fit the Galaxy S21+, S21 Ultra or S21 FE.
Does it fit the Galaxy S21+?
No. The S21+ has a different frame and flex layout. This part is for the Galaxy S21 only.
Will this fix a volume button fault?
Check the photos against your old part. This flex is listed for the power button. Volume faults may need a different part.
Is it made by Samsung?
No. It is a brand new, OEM-quality part made to fit the Samsung Galaxy S21, and it is tested before dispatch.
Should I fit it myself?
We recommend professional installation. The back glass has to be heated and lifted, the battery must be disconnected first, and small flex cables are easy to damage.
How quickly will it arrive?
Orders placed before 4pm on a working day are dispatched the same day from Manchester by Royal Mail Tracked. Delivery is free on UK orders over £5. You can also collect from our shop at 33 Moulton Street, Manchester M8 8FQ.
Prepared by the Supreme Phone Parts team, Manchester. Last updated September 2026.