They can go from debris or water in the motor too. Me personally, I would put props on and make sure they spin freely, then try again with DJI Assistant 2. If you still get the ESC error, it's probably time for a trip to the service department...
Note that when you connect your Mavic 2 to your computer via DJI Assistant 2 for Mavic, it can be very fussy about what USB port you connect to. If you plug in, but the screen still shows you the USB connection page (and you have no "Connected...