GMC envoy

Need help. My mom's car done a "Christine" move
one her yesterday. It is  a 2008 GMC envoy. Doors
wouldn't unlock or open, all lights were on, air
changed to full blast heat and she sure didn't need
the heat on when it's almost 100 degrees outside.
she tried everything to get the stuff to turn off but
nothing worked. The unlock pad wouldn't unlock it
either.a he had to drive on home to have my
brother get the spare keys that unlock button on
those wouldn't wrk either he had to put key in the
door to unlock n open driver side to let my mom
out. They had to undo battery cables for awhile n
when put back on everything was back to normal.
What could caused this to happen