I have experienced the exact same problem twice, first time about eight months ago, and now just an hour ago. Both times when stopping in a parking lot, putting the car in neutral to let a passenger in, and then failing to get it in gear again, all buttons and screen unresponsive, engine running and effectively blocking other cars from passing. Quite effectively raising the stress level of the driver as well, I might add.
I managed to get hold of a MG car mechanic via phone the first time and was told that the only solution was to reboot the motor ECU, by pressing the start/stop button for 60(!) seconds. Worked both times.
Apparently this is a known issue, but lacks a firmware fix. I had the car back at the dealer’s after the first occurrence and the only update they provided me with was for the DAB- radio. Not impressed.
I find this car disappointingly unreliable. I have had all screens go black twice while driving, automatic high beam lights turning on at random, as well as the radio deciding to blast full volume also at random, and car play dropping its connection frequently (different phones and cables tested).
And don’t get me started with the fuel economy. At highway speeds I rarely go below 8.0 l/100km, quite far from the 2.0 advertised. When asking my dealer I was informed that the number was calculated on a flat surface, at 20C, and at an average speed below 49 km/h, effectively meaning running in EV mode most of the time. I should have read the fine print…
Thankfully I’m on a lease contract and will not be stuck with it forever.