Did not winterized

We had the coldest temperatures on record here in the DC area this winter. I'm sure Davidsonville was a little colder. I think your buddy is in trouble.

Bruce

My biggest concern would be that some inaccessible fitting inside a wall has cracked and you won't find it until the rot has done a lot of damage.

It’s possible nothing will be broken but that will be a highly unlikely scenario…
there will almost assuredly have been water trapped in some valves or the pump, and some water collecting at low points throughout the piping…
they don’t take the time to be sure all plumbing will actually drain to the low point drains… especially if the unit was not completely level when draining…

If he didn't blow out the lines then there could be stuff busted almost anywhere. I would pressure test the supply side and see whether it holds air before I pump water through it.

The water pump and faucets may have frozen and broke.
Please, let us know what happened.

I don't know...but if you're there when he pressures it up for the first time, please do report back about what you see!

1. Busted supply lines.
2. Busted drain lines.
3. Busted waste tanks.