I replaced the starter solonoid, and rebuilt the starter on my 94 Buick Regal. It still won't crank. Battery is showing 12 volts. Jumping doesn't work either. Starter tests fine at the auto parts store. What else could be wrong?

. Remove and fully charge, or replace, the battery. Most auto parts stores will do this for free.

. Read the link below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235560

May be your ignition. You can also try running a wire from you altinator to the starter and see if that helps. Is your battery posts clean? You say your battery had 12 volts in it. Did you take a tester to your starter and see if you are getting 12 volts there as well? Did you remove and not replace any shims when you took the starter out?