curiously though, i forgot to mention this before, i still got that "error" prompt when it booted up.
What was the error? I've heard of a few people that installed the OTA through System updates having Custom Recovery, however it is not possible to Flash a copy of the OTA through Custom Recovery. How did you downgrade? Did you use an FXZ, Recovery Backup, Utility?
Shortly, I am going to FXZ 9.16.9 and see if the update will push clean threw that way, with the 9.20.1 update. Hopefully, it works.
I must be missing something with safestrap. After installing it, I created a rom slot, created a backup of the stock rom, restored it into the just-created rom slot, set that as active & rebooted. It hangs after starting to boot. Since I only did the latter steps as a confidence builder (that the backup was actually usable in case I trashed something), I can't say I'm pleased with the outcome. Any idea of what I did wrong? Or am I misunderstanding what safestrap does?