I had a similar problem on our ZS EV Gen1 when it went into the dealers to have a simple service and the wiring loom in the drivers door, replaced under a recall.
While the loom was being replaced, the key was sitting on a table very close to the car.
When the work was complete, the car would not respond in any way shape or form.
Every time the 12 volt battery was reconnected, it would instantly active the alarm system.
The dealer then assumed it was a problem was the new wiring loom and therefore they reinstalled the old loom.
This did not fix the problem either !.
They then enlisted the help of MG CS and they asked for the data pack to be uploaded.
After a couple of days, I received a call from the dealer asking if I could bring the spare key to the garage.
To the relief of the workshop manager, the car jumped straight back into life !.
They where instructed to recode BOTH keys as apparently, they have to coded as a matched pair.
MG CS had told the dealer that because the loom had been disconnected for replacement, the car had perceived this as a possible attempted theft and then scrambled the code in the first fob.
CS told the dealer that the key SHOULD have been kept well out of range of the car when the job was carried out.
The dealer said that there was no mention of this advice in the digital workshop manual.
I know that sometimes owners provide BOTH keys when submitting there car for work to be carried out.
I am SO glad that I did not do this !.
@Robert Gardner you will need to take your car to your local MG dealer for recoding
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