Speaking about vehicles in general, the first thing to check is
poor contact at one of the battery terminals.  Is either loose
or corroded?  If one's loose, just tighten it.  Otherwise you
might want to remove the leads and clean and tighten
everything.  But you might need a radio unlock code to get the
radio working again.

An intermittent bad connection in the starter motor solenoid is
the next most likely cause.

John