Clock sometimes at 12 and cd player clicks

Had a oil and lube truck was fine going in but
the next morning went to work turned off the
engine tried to start it up again and it was
pitch black and wouldn't start. After work
everything was fine. W/in the past 3 weeks it
would turn over just fine and sometimes the
CD player would click and radio is at12:00 no
matter what time of the day it was. But it
would turn over quickly and sometimes
slower. What could've happened during
maintenance time?