Like you recently my summon has failed, (2020 M3P with FSD) I only used it when out shopping as i always park as far away from the shop as possible and I reverse into a spot - usually meaning the boot cant be accessed until the car is pulled forwards.
Now Summon has never been very good but standing by the door of the car I could make it move forwards a few feet and then load the boot up.
The last time i used it that way was about 4 to 6 weeks ago and it was fine, Last Saturday I tried it and The lights come on, the indicators flashed, the steering goes from left to right - I hear the noises as motors start up (not drive motors) and then it all shuts down.
I didn't know if the issue was Tesla breaking it with an update or my car just being temperamental - as usual, and perhaps needed a reboot - which I haven't done - so now, with your post i do know Tesla broke it and will fix it ----- eventually (eventually said like Manuel - Faulty Towers)