Is Firestick 4k at 8.1.5.5 now completely unable to block updates?

I have a Firestick 4k that is updated to 8.1.5.5 - it now seems impossible to update via ADB to block the OTA updates. Previously 2 months back I did update a FS using ADB and installed Projectivy - that unit still works fine but now I’m not able to update 2 other Firesticks 4k that I have.
If I were to do a factory re-set and enable ADB before it connected to Amazon will that work? - or is it time to move on ? I recently got an Onn 4k Pro device - seems to work great but WAY too many ads.

2 posts were merged into an existing topic: New Fire OS Update Breaks Custom Launcher Use