Hi, so sorry to hear you are having this issue. I had all the EV batteries replaced along with some other components. I have not had any issues since. The warning has not appeared again. However unlike your issue when the warning came on my vehicle I could not start the car at all, it was a dead brick. There was definitely something wrong with my batteries, and since the replacement I can see them charging from re-generation (braking etc...) and that never happened before the batteries where replaced. The 12v battery was also replaced as part of the work. Hope this helps but if you need any further info I will happily try and help.
Hope you get sorted soon.
Hope you get sorted soon.