Okay, my 01 GC wouldn't start yesterday.  I put a battery charger on it, but
the battery wouldn't take much of a charge.  I jump started it, and drove it
about 10 miles.  On the return it started fine.  Tried it 4 hours later and
it wouldn't start.
Again, the battery wouldn't take much of a charge.

I bought a new battery.  It was dead (or so I thought).  I charged it
overnight, but it still wouldn't start.  I took it back as defective.

Bought a different battery and a new charger/starter.  It wouldn't start on
the new battery.  I put the new charger on the new battery; the charger said
the new battery was 85% charged, and quickly brought it to full charge.  Car
still wouldn't start.  It wouldn't even start when I set the battery charger
to start.

It makes a small thunk sound, but then nothing happens.

So, what is my problem? (Starter solenoid, right?  Dont' know what it is,
but have heard that it is the starter solenoid if it isn't the battery.)
How do I get it fixed if I can't get my car started to get it to a repair
shop?

Presumably the old battery wouldn't take much of a charge because it was
fully charged.  Oh well.

Should I try jump starting it again with my other car?  Worked yesterday,
but I hate jump starting cars; always picture the battery blowing up or
something.