One of the good features of the Lenovo Tab M7 (Gen3) tablet is that it can be shared among many users. The first account that is created is the admin or the system user. Multiple other users can be added using the Multiple users option in settings. However, it has a fatal problem (as described below) that happened every time I used it - so DO NOT USE THIS FEATURE, it is garbage!
I had added an additional user to the tablet which had its own Google account and apps. Switching between the admin user and the second user was working fine for many days. However, one day while I was inside the second user I could no longer go back to the admin user! The admin user was present in the lock screen, but it was greyed out. Many users have faced this problem as seen here.
One suggested solution is to download Android Platform Tools and use the
adb tool to debug and fix. However, USB debugging should have been enabled on the tablet (before it went kaput) for this to work. My tablet would not even be recognized as USB device when plugged in, so it did not work.
Lenovo has a Rescue and Smart Assistant (RSA) tool that is supposed to work with this tablet. But again, with the USB debugging not working, this was not an option for me.
Thankfully, a factory reset using the physical external buttons worked and I was able to at least start from a fresh slate again.