Several questions:
So you say it won't start than you say all it does is click.
So no crank, no start? (This is important) Big difference between no start and no crank, no start.
You state the batteries checked ok? How were they checked? With a VOM or with something that can put a load on them?
Are they the original batteries?
Have the battery connections been checked?
No crank, no start, 98% of the time it's going to be batteries, connections or starter. Someone is going to have to figure out which one of the 3 is causing you problems. Let us know what you find.