If 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 or a '+' symbol and unable 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.
- You need to 'forget' the micro:bit, in the Bluetooth settings on your mobile device and pair it again.
The steps to follow are slightly different if using the iOS app for iPhone/iPad or Android app.
It should now work again with the app. For any further issues, please open a support ticket.