DIAGNOSIS A blinking green power light is the printer's generic 'error' state. It's frozen because it encountered a problem it can't get past, often during startup or a print job.
FIX We need to do a full power cycle to clear its memory. 1) Unplug the power cord from the back of the printer. 2) Also, unplug it from the wall outlet. 3) Wait a full 60 seconds—this lets all the capacitors drain and the logic board reset. 4) While it's unplugged, check that there's no paper jammed anywhere and that all covers are fully closed. 5) Plug everything back in firmly and turn the printer on. It should go through its normal startup sequence.
IF THAT DIDN'T WORK If the blinking resumes, there might be a more serious hardware fault. Listen carefully during startup. Does it make its normal noises, then stop and blink? Or does it just blink immediately? An immediate blink with no movement could point to a failed printhead or main board.
HEADS UP Never just turn the printer off with the button when it's blinking. Always pull the plug. Forcing it off mid-error with the button can sometimes corrupt its firmware, which is a much bigger headache to fix.