94 Camry Completely Dead

Mu nephew killed his dad's truck so we tried to
jump start it. It was dark and we think we switched
the terminals on my car. My car ran fine for the
next day. Then when I would go to start it,
everything would go black. I would take my key out
and put it back in and it would make the chime but
when I turned the key agaim, everything went
black. So we thought the battery was dead. We got
a different used battery but it didn't want to start.
We noticed the battery terminal connector for the
negative was corroded and cracked so we
replaced them both. It ran fine for a day. It started
and ran fine when I left for work this morning and
when I got off. When I went to leave my mom's it
didn't want to start so we jumped it. On my way
home the radio cut out and then it completely died
and I lost all power. Now it won't do anything and
it's stuck in park. We tried to jump it again but its
completely dead.