Power and Volume Button Flex Cable
Samsung Galaxy M40 Power and Volume Button Flex Cable Replacement
- Fits
- Samsung Galaxy M40
- Fixes
- Dead side buttons
- Quality
- Brand new, OEM quality
- Fitting
- Professional install
Overview
What this part is
On the Galaxy M40, the power and volume keys press against small switches on a thin flex cable inside the frame. Drops, liquid and years of pressing can tear the flex or wear out a switch, so a key stops clicking, sticks, or does nothing.
This part replaces that flex cable. It fits the key positions in the M40 frame. The physical button caps on the frame are not included; if a cap is missing or broken, that is a separate repair.
Compatibility
Specifications and compatibility
- Part
- Power and Volume Button Flex Cable
- Compatible with
- Samsung Galaxy M40
- Model numbers
- SM-M405
- Does not fit
- Galaxy M30, A70 or any other model
- Fixes
- A dead, stuck or unreliable power button or volume keys caused by a faulty flex cable
- Does not fix
- Missing button caps, software freezes, charging or screen faults
- Quality
- Brand new, OEM-quality power and volume button flex cable for the Galaxy M40. Tested before dispatch.
- Brand
- Unbranded, compatible with Samsung Galaxy M40
- In the box
- 1 × Galaxy M40 power and volume button flex cable.
- 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 power button does nothing, so you can only wake the phone by plugging it in
- Volume up or down does not respond, or changes volume on its own
- A key only works if pressed hard or at an angle
- Side keys stopped working after a drop or liquid spill
How to check your model
Open Settings › About phone. The model name should read Galaxy M40. The model number starts SM-M405.
The M40 has a 6.3-inch screen with a camera hole in the top left corner.
Professional installation
How a technician fits this part
- Power the phone off and remove the SIM tray.
- Warm the back cover to soften the adhesive, then lift it off the M40 carefully.
- Remove the screws on the inner cover and disconnect the battery connector first.
- Unclip the old button flex from the frame and main board, noting how it is routed.
- Place the new flex, reconnect it and test power, volume up and volume down before closing.
- Reconnect the battery, refit the inner cover, apply new adhesive and press the back cover down 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 Galaxy M40?
Yes, if Settings › About phone shows Galaxy M40. The model number should start SM-M405.
Does it fit the Galaxy M30 or A70?
No. It is listed for the Galaxy M40 only. The M30 and A70 have a different layout.
My button cap is missing. Is it included?
No. This is the internal flex cable only. It fixes keys that do not respond when pressed. A lost or broken button cap on the M40 frame needs a separate part.
Is it made by Samsung?
No. It is a brand new, OEM-quality button flex cable made to fit the Galaxy M40, and every part is tested before dispatch.
Should I fit it myself?
We recommend professional installation. The M40 has to be opened with heat, the battery disconnected, and the thin flex routed without creasing it.
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 from £5.
Prepared by the Supreme Phone Parts team, Manchester. Last updated September 2026.