I bumped some wire under the dash replacing a turnsignal flasher. Car wouldn't start with key, had plenty of battery. Simple way to make sure everything is in working order outside of the rat'snest of wiring that could take months to fix. This is more of a temporary solution, but you could easily add a fused wire going into the cabin with a pushbutton to start.

STEPS

1. Open fuse box
2. Remove starter relay (diagram on relay box cover)
3. Turn key to ON (NOT START OR ACCESSORY)
4. Insert one end of wire into one of the two slots being jumped
5. Make sure car is in neutral or PARK
6. Touch other end of wire to terminal, let crank until started.
7. Remove wire and put cover on fusebox
(You don't need to put the relay back if you will be doing this often. No voltage flows at all when the relay is removed)

I do not own the MUSIC IN THIS VIDEO