Quick troubleshooting guide:

Code accepted but the counter does not open or the door does not open: re-enter the reservation code once and confirm.

The code or badge is not accepted:  check if the date and time displayed on the screen is correct, if it is not correct call technical assistance.

The screen is frozen or the display is abnormal: press the Reset button at the bottom right of the green round case of the M'Key. If it's a touchscreen, double-tap your service logo at the top left of the screen.
Charging does not start:  if there is a badge associated with the keys, iron the badge, otherwise re-enter your code. If the charge still does not start, disconnect the cable then iron the badge or type the code then reconnect the cable on the terminal side then on the car side.