Just to double check that your device is affected and not just entered download mode as an exception, try to force restart it:
- Press and hold Volume Up & Power (lock) buttons together for about 14 seconds
The phone will reboot and should start normally. You are good to go if it works.
Method 2: Change the active slot to the inactive one
- Download and install Nokia USB Drivers on your Windows PC.
- Download Minimal ADB and fastboot to communicate with the device in download (fastboot) mode.
- Connect the phone to the PC using a USB cable.
- Open the minimal ADB and fastboot folder and run “cmd-here.exe”. It will open the Windows Command Processor.
- Check that your phone shows up by typing: fastboot devices The expected response is your device’s serial number followed by the term fastboot.
If you get an empty response, then your device is not detected. Please check the drivers.
- One more test, reboot the phone. As per a comment (below), this fixed a Nokia 7.1 without any loss of data. Type the following and press Enter. fastboot reboot Your device will either start up or come back to download mode. Good if it starts up, else continue the steps below.
- Now check your current boot slot, type: fastboot getvar current-slot
- Change to the inactive slot. If your current slot (previous command) is a, then run the following command: fastboot –set-active=b If your active slot is b, then run the following command: fastboot –set-active=a Some phones use the underscore “_” prefix for the slots. In that case, modify the above commands with the underscore. For example fastboot –set-active=_b
- Reboot the phone using the fastboot command: fastboot reboot
- Your phone will show a warning “Can’t load Android system. Your data may be corrupt. If you continue to get this message, you may need to perform a factory data reset and erase all user data stored on the device.“
- Use volume keys to highlight “Factory data reset”. Then press the power key to select it. Select yes on the next screen to confirm the data wipe.
If you are lucky, then your phone will start up normally after the reset.
In case the fix does not work, then you need to send the phone to Nokia care for service.