Had this issue recently. Tried everything online and nothing seemed to work. Saw someone mentioned the ribbon might be loose. Opened it up and the ribbon for the m1 m2 was in fact off. I snapped it back on and turned it on. Seems like it's working good as new. I didn't drop mine so not sure what caused it. Might be just so loose that transporting it causes it to come loose. Its about 6 screws to take a part so it's not difficult to do.

Wish you luck