Well,
I think I'm right in saying there are NO relays in the or ignition circuit.
Same as to fuses- WAY too easy to fail a relay or blow a fuse, and if you dont have a spare your car cannot be started.
I have never heard of voltage destroying a starter, at leats not in a regular car-
is it possible you have wired the starter / solenoid wrong?
If you had something in the 'voltage' area strong enough to destroy a starter, it would fry the whole circuit TO the starter first. Maybe your solenoid-to-starter connection is wrong.
Try this:
Get another starter if you're sure you've blown the one you have- ALSO get a remote starter button (has an insulated push button and two long wires with alligator clips at the end) they're usually under $10.
With your next GOOD starter, bolt it in and attach the battery positive to the solenoid as normal- LEAVE the rest unconnected.
Make SURE the engine is grounded, even ground teh battery to it if needed.
You then *clip one of the wires from your remote button to the large + terminal (battery) on the solenoid then the other *clip on goes to the PUSH on spade terminal on the solenoid (the only other connection).
Pushing the button SHOULD be like turning the key.
Always in Neutral. Always in Neutral. Always in Neutral. Always in Neutral. Always in Neutral.
You should be able to crank the engine over easily like this- if you fry a starter using this method you better get a priest you have bigger problems than we can help you with.
_Bob O