Hi
Lets start at the beginning.
Make sure your battery is 100% charged.
Check your 12volt cables, and just as important, your grounds !. The grounds are from you Neg battery post, to the body, and to the motor (usualy at the transmission tail). These
WILL heat up and
BURN, with a 12volt short.
Check the 12v connection at the starter, check for signs of loose or overheated wires.
Get a schematic and check your power 12v "in" and power 12v "out" at the ignition switch electrical connector. Look for signs of over heating.
Check the schematic, for the 12v and ground coming in to the relay board.
I don't have a electrical diagram....would be easier to explain...
Report back what you find, we'll get ya thru it. Lots of possibilities including the board may have fried
but some thing to check before dishing out $$$.
Later