If you find that the micro:bit is not letting you update it after using one of the apps, it might be because the last Bluetooth flashing process was unsuccessful.
This can cause the micro:bit to appear unresponsive, with a blank screen and not able to enter pairing mode.
If this happens,
- Connect the micro:bit to a computer via USB
- Open makecode.microbit.org in a new browser window
- Download and flash a simple program to the micro:bit
- 'forget' the micro:bit, in the Bluetooth settings on your mobile device and pair it again.
It should now work again with the app. For any further issues, please https://support.microbit.org/a/tickets/new