The fuser lock mechanism engages every time the printer powers down. The more you cycle the power, the more you wear the plastic cams. Leave the printer in Sleep mode.
Before blaming the locking block, rule out these common FTF culprits:
: Once the "Flashing finished" message appears, disconnect the phone and power it on. It will perform a fresh setup without the previous lock. Alternative: Hard Reset (No PC Required)
FRP lock removed. Device booted normally to home screen after final reset.