You can also post it for sale online stating the buyer is responsible for moving it and properly disconnecting plumbing and electrical. 

I had their electric and water disconnected. 

Successfully disconnecting while still leaving my team and clients in a good place? 

Anyways, the major function of the PM is to disconnect you from the tenant, and you would be circumventing that purpose by putting yourself out there as a source of relief.

I am a heating contractor and I work on baseboard systems, but diagnosing a problem without being on the site is difficult because we need to do process-of-elimination.The first thing I would do is disconnect the wires at the solenoid valve.

A partial list was , fireplace built wrong unsafe , no electrical disconnect on outside of house , no gfci breakers in bathroom , garage or outside outlets , moisture around foundation , basement steps not built to code , no escape window in basement .  

If it doesn't turn on at all (no power) check where the electric connects it may be a simple disconnect. 

(ie sewage piling up under trailer due to disconnected pipe) You (someone) needs to get under there with a shovel and bucket and clean that crap up.

You'd have to basically run new t-stat wire to one of the units (the one that feeds the area from an air perspective) and abandon (disconnect) the terminations of the existing wire at that unit.Watch some youtube videos for how to do those control wire terminations.

Turns out the gas line to the fireplace is old and disconnected.