Seeing as no one has replied, you need to update the phone or have something in the _b partitions or else you get a black screenI have a Moto G Play 2021 Guamna and have taken the following steps.
1) unlocked the bootloader
2) enabled USB debugging
3) downloaded aosp_guamna-img-eng.electimon-Feb-Week3.zip
4) changed the name to aosp.zip
5) rebooted to fastboot and typed the following
fastboot update aosp.zip
I get a bunch of "archive does not contain *.sig" but it continues on and eventually says it's completed. When I reboot the phone I can see the screen is on, but it's blank. I can use ADB shell and see that there is a unix looking file structure.
I have no idea what to do next. Any information anyone can give would be helpful. I don't mind factory resetting or using the Lenovo rescue tool, I bought this phone to learn on.