Truck won’t start

I put a new transmission in my truck and had trouble with
start going back iin and had no power at the time. So I
pulled the starter back out and the wires were bare
copper so I  wrapped them up. And it started up fine for
about a week then one night went to move the truck. And
nothing no power to it. So I thought the battery was dead
and hooked a battery charger up to it. And still nothing
played with it for about a hour checked all the fuses and
they were fine. Then it just started up like nothing was
wrong with it drove fine. A couple weeks went by and
went out to drive it and again nothing no lights NOTHING!!
So I hooked up the battery charger yet again. And still
nothing. Played with it for awhile and it started up but this
time my gages were going crazy!! And now I can’t get it
started at all. All the fuses are good. Could it be the starter
or the grounds came off the truck?? I have no idea, please
help.