With a test light ck for battery voltage on the smaller wire at the starter, It should ONLY have voltage with key in start position. If no voltage and starter stays spinning, you have bad starter

If you have voltage in any position besides crank.
Ck voltage at the relay yellow wire. That should only have voltage with key in crank position.

If the voltage on said yellow wire goes away after releasing the key. You have bad relay
If it HAS voltage in any position besides cranking position you have bad wiring between switch and relay