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Flashing a new micro-SD card

The following steps describe how to flash a micro-SD card with the latest version of FunKey-OS. This must be done before switching micro-SD cards inside the console.

Note: Everything on the micro-SD card will be lost, be sure to save your data.

Download the latest FunKey-OS image file

Get the latest "FunKey-rootfs-x.y.z.img" SD card image file directly from here or from the bottom of the latest release page in the "assets" section:

Github Release

Flash the micro-SD card with balenaEtcher

  • Download and install balenaEtcher for Windows/Mac OS/Linux from

  • Run balenaEtcher and click on "Flash from file" to select the FunKey-OS image file

  • Insert the micro-SD card in your computer and select the SD card drive (balenaEtcher should automatically detect it for you)

  • Finally, click Flash

  • You'll see a progress bar. Once complete, make sure the flashing was successful, otherwise retry to flash the SD card. The program will automatically unmount the SD card so it's safe to remove it from your computer.


Switching micro-SD cards

On the FunKey S, the micro-SD card was voluntarily placed against the casing so that it has no degree of freedom and cannot move by accident during the eventful life of a keychain.

Removing/switching the micro-SD card was nevertheless designed to be pretty straightforward and only require a standard Phillips screwdriver (PH0) and optionally some tweezers.

Please follow the steps below carefully:

STEP 1 - Removing the screws

Before opening Remove the screws Screws removed

Using a standard Phillips PH0 screwdriver, remove the 2 screws on the back of your FunKey S.


Be careful to use the correct screwdriver head size and type to prevent damaging the screws (do not use JIS screwdrivers!). FunKey Project is not responsible for replacing damaged screws.

STEP 2 - Opening up the console

Pull up hinge first Pull up the plastic buttons Console opened

Carefully remove:

  1. The plastic back of the console by pulling up the hinge side first
  2. The L/R plastic buttons by gently pulling them up out of their axis
  3. The keychain lanyard and axis


Be careful not to damage the L/R switches on the circuit board!

STEP 3 - Exposing the circuit board

Lanyard Axis Lift the battery Get the battery out of the way

Remove the keychain lanyard axis, as it may fall off when opening.

Lift the battery (but leave it connected) to expose the circuit board.

STEP 4 - Accessing the SD card

Pull PCB by its micro-USB port

By grabbing it by the micro-USB port, gently pull up the circuit board until you have access to the SD card.

STEP 5 - Switching SD cards

Remove the micro-SD Insert the new micro-SD

You can now remove the old micro-SD card from its socket and insert the new one (previously flashed as described in the 1st part of this tutorial).


You may need to use some tweezers and pull with some strength in order to remove the micro-SD card from its socket, as it is strongly inserted to prevent loose connections.

STEP 6 - Reassembly

Insert speaker first Do not insert hinge first

Insert first the speaker into its location in the casing before putting the circuit board back in the case, like in the pictures.

Reassemble the console by following the previous steps in reverse order.


Be careful not to damage the switches on the circuit board when putting back the L/R plastic buttons.