Curious.
Did they check your alternator output?

I have seen many of theese cars lose power and die due to a bad alternator.

Your car can do all kinds of strange things when the alternator no longer powers your vehicle control modules, and the car runs as long as it can on battery power till that runs out.

In the meantime you can have all kinds of weird gremlins going on.

In most cases the (SRS) light will come on as well.

Make sure you check alternator output.

The tech may have been lazy and not even checked it, it happens.