Wacko AI

Not to be confused with Yakko or Dot...

Just had the DG replaced (went precessing 60 deg on a 90 deg turn)
yesterday. Ran the engine up and taxi'd to the ramp from the shop.
Things looked ok - no, wait! the AI is upside down. Now, I'm
used to seeing it canted to the right before everything is run up
to speed, but upside down? Waited a few minutes, nothing, but
nothing changed. Unfortunately, the shop was closed by now so I
left it on the ramp and took the bus home.

Much more mystifying...after ALL power was off, engine off, key
out, battery off, etc. the AI dial was spinning. Yes, that's right,
spinning like a top. Fast. And it didn't seem to slow down, either.
I didn't time it, but it just sat there spinning for at least
5 minutes.

This is really surprising for a number of reasons.
1) I had spent 2 hours flying before taking it to the shop with
no indications of any problems.
2) A new AI installed in 2003
3) #2 occurred because the old AI sloooowly died on an IFR lesson
back in 2003. It was very noticeable, too, but not like this!

I would not have expected the AI to just quit without any warning.

Any suggestions? I haven't heard from the shop this morning (they're
not open yet). I'm thinking something got jarred loose when the
new DG was installed.