1994 buick lesabre

New battery dead, faulty starter relay or solenoid. Try jumpers

Have you changed the solenoid yet? Relays involved might need replacement. How old are the battery cables?

I'm not sure whether on your car your voltage regulator is a separate unit from the alternator, but if it is separate, change it. Somewhere along the line they became an integral unit.

Is your battery charging? When you try to start it, what is the voltage range of your battery as you check with your voltmeter?

Coincidentally, how old is the starter?

We could eliminate much by using jumper cables, but I guess we don't want to do that.

Cables might be a few thousand miles long if my car is the jumpee.

Did you connect the earth strap?