Have you checked the battery status on the AXS app? When it stopped working, could you manually shift using the derailleur buttons? Did you check the status lights on the shifters when it stopped working?

As it appears to be working now, I would closely monitor the battery status, especially the rear derailleur as that has the brain which pairs everything else.

If it suddenly locks up again I would check the shift paddle indicator lights are working and try to shift each derailleur manually with the buttons (one click for higher gear, double click for lower gear on the rear). If your rear derailleur was in the highest gear when it locked up then a single button press would not shift gears.