DIAGNOSIS F01 is the communication error code between the main control board and the user interface board. The washer can't start because these two brains aren't talking.
FIX First, unplug the washer from the wall outlet for a full 5 minutes. This forces a hard reboot of all the electronics. Plug it back in and see if the error clears. If it does, you're good to go. If F01 comes right back, the connection between the boards is likely compromised. You'll need to access the control panel area (usually by removing a couple of screws on the back of the top panel) and check that the flat ribbon cable connecting the two boards is fully seated and undamaged.
IF THAT DIDN'T WORK If reseating the cable doesn't fix it, one of the boards has probably failed. On this model, it's more often the smaller user interface (UI) board than the main control. You'd need to replace the faulty board.
HEADS UP Before you go ordering parts, double-check that your home outlet has power. It sounds silly, but a tripped GFCI or circuit breaker can sometimes cause weird startup errors that mimic F01.