The chances the battery is bad are verry low… Id say its the solenoid, but if you connected the started DIRRECTLY to the battery, and nothing happned… That would be a bad starter, with NO load on the starter, it should turn no problem on a dead as hell battery. So, you headlights turn on? If so, batterys fine… Just leave the headlights on and try to start it, if they stay lit and all you hear is a click, the battery is fine, the starter isnt drawing power…
This should be a real easy fix, but youd need someone with electrical knowhow to go there and it should take like 2 mins…