Motorcycle Repair: Starter wont stop spinning, starter solenoid, fxrp

Question
87 FXRP. Just installed an a new ignition to fix a stalling issue. An excell with timing now.
Now a new issue. Crap. Always something and killing me.
Started the bike and heard the starter still spinning. No grinding at all.
I shut her down and it didn't stop. I had to quickly remove the negative from the battery to stop it. Scary Even with the key in my hand it didn't stop.  I have a new cellinoid. About new everything even battery.
The battery was getting very hot.  I hear so many different answers on the HD forum.
Hopefully a cheap bad relay or starter switch. But should I consider a ground quick release breaker.
I can't afford $75 an hour any more.  I am all in on this classic.
New engine too.  
Frustrated. The ol lady is afraid we will get stranded.
This seems to happen and no one thing seems to be the answer
Thanks.

Answer
If you starter still spins when you release the starter button then you have one of 3 problems. Starter button is sticking, bad starter solenoid, or weak battery. Even though you have a new solenoid it can still be bad and this is generally the problem.
Good luck and happy riding
Mike