2001 Chevy Silverado 2wd 1500

My bf connected a 2nd battery in my truck using
jumper cables that had the clamps still on them
and he set the battery on the opposite side of the
motor under the hood without strapping it down.
Last night as we where driving we hit two bumps
and the headlights dimmed and the truck shut off
but with lights still working. Thought it was out of
gas so we got gas for it but the fuel pump won't
kick on unless we bypass it but the truck still won't
start, it tries to crank over but just won't start
unless we use starter fluid but even then it won't
idle and runs like crap. What else could be wrong?