If you find that your keyboard or mouse are unresponsive after flashing the micro:bit device via webUSB, it is possible that they have been force ejected from the machine.
This can happen when you are using Antivirus software that scans USB ports and force ejects currently connected devices or when you are using third party drivers with your mouse/keyboard.
To resolve the issue:
- Check if you have any antivirus software running. If so, is it possible to add the micro:bit to an allow-list or disable it from being scanned?
- Remove any USB devices that you are not using
- Restart the computer with the micro:bit plugged in