Nokia 7.1 won't boot after Google Security Patch update My phone (Nokia 7.1, Android 10) downloaded a Google Security Patch update over night and asked me to reboot the system for installing the patch. But after the reboot, it said that the system is corrupted and the phone needs a factory reset. I don't want to lose the data on the phone.

I can get the phone into Download mode and communicate to it via fastboot and I tried to use adb to sideload the original Android 10 image (29ad19....zip, which is build 4_08D), but it won't let me install it because the build timestamp is older than my current system's build timestamp and it refuses to let me downgrade.

I tried re-installing the latest security patch (4_08F) from here via adb but the system says that this patch was meant for 4_08E not 4_08F. This is confusing because if the system had trouble installing this patch in the morning, it should have stuck with 4_08E, right?

My questions to the community are as follows:
1) Can I force my phone to downgrade and install an older system without losing my data? If so, could someone point me to the correct instructions?
2) Are there newer updates for Nokia 7.1 that I've not found which I should be trying to install?

Thanks!
It is a fairly common sight on a "Nokia 7.1". Did you try this tutorial already? The slots can essentially take you 1 version behind and you can then try booting. Sometimes that works (as in the comments sent by many). And since you want to preserve your data, there's even lesser chance that it will work, but it can.

If not, what you can try is to go one version behind (by changing the boot slot -- fastboot --set-active=a or b as needed) and then try to sideload the latest update via recovery again. As with updates, they can only take you forward and not backwards. The 408F is the newest update for the phone and you cannot find an update newer than that. When you'll change the slot, you'll be on 408E and then the 408F should install just fine. 

As about your question about how the update got installed, it's the beauty of A/B devices, but the issue isn't with installing the update, it was done successfully. The issue is more of the device not managing to get its encryption running after the update has finished installing. The system feels that the update was successfully installed, but the phone clearly knows that something went wrong with the data encryption/decryption process.

In case changing the boot slot and then installing the update doesn't help, then you're left off requiring full firmware installation. You can send to Nokia or buy a remote flashing service. If you still haven't done a reset until this point, then the service can try to help bring your phone to a bootable state where you can backup your data.