The first new cars in a long time. Completely new train systems. Check. Check.

The computers crash and have to be rebooted. Check.

You expected what, perfection?

FWIW, Sacramento had that problem with their new CAF light rail cars in the mid-2000s. Cruising along when it would suddenly become a glider, until the brakes took hold and stopped it. Initially, drivers would be puzzled and would try rebooting various things while talking with Central and Maintenance, for 5 or 10 minutes. It usually ended with the expedient solution, which became routine (until software was fixed): drop the pans and cold-start the train. IOW, pull the plug taDA! Worked every time, took about 2 minutes, back on the road again.

BART, unfortunately, doesn't use pantographs on overhead wire, so things are more complicated. Can the 3rd rail shoes be raised or all power otherwise disconnected easily? If so, that might be a quicker way to restart the train than to go through a bunch of other processes.