DIAGNOSIS That flashing power light is the printer's way of saying it's stuck in an error state, usually because it's waiting for you to acknowledge a paper jam or an empty ink cartridge.
FIX First, power the printer completely off by unplugging it from the wall for 30 seconds. While it's off, open the rear access door and gently feel along the paper path for any scraps of torn paper. Open the front cartridge access door too, and make sure both cartridges are firmly seated in their cradles. Plug it back in. If the light is solid, try a print. If it's still flashing, check the display screen or the HP Smart app on your phone; it should now show a clearer error message like 'Paper Jam' or 'Ink Problem'.
IF THAT DIDN'T WORK If the light keeps flashing with no clear message, there might be a carriage stall. With the printer on, open the front cartridge access door. The printhead carriage should move to the center. If it's stuck, gently nudge it to the far right to free it, then close the door.
HEADS UP Never yank jammed paper out backwards. Always follow the paper path in the direction the arrows point inside the printer, or you can tear off a piece that's nearly impossible to find later.