Typical basic trouble shooting is to inspect all connections, look for loose connections and oxidization, any warm receptacle plates or light switches, smells of melting wire or plastic, signs of burning/arcing/overheating such as blackened areas around receptacle boxes or anywhere there’s a connection, or flickering lights not associated with the bulb not being screwed in tightly.

When I asked about the job times, they agreed to reduce the doorbell charge but held firm on 3 hours for the faucet because they claimed it took time to troubleshoot. 

That's step one on just about every troubleshooting guide for an HVAC unit....

The general synopsis that I am seeing from posts like yours is:If I keep the tenants up to date on the troubleshooting process and show that work is being done to resolve the issue, I'll be fine. 

My short-term rental is out of state but I manage it remotely (mostly guest communications and troubleshooting issues) and if I include in that the time I spent getting it ready to rent, I would say I materially participated and even more than anyone else (i.e. cleaner).

We have a troubleshooting video and a plumber/handyman who lets us know if we should charge back to the tenant.

And while this install seems pretty straightforward, if it doesn't go as planned, your guest will have to deal with the cable company for trouble shooting.

One does not imply the other.Everytime someone is having a hard time here, they start to troubleshoot but make complete random decisions based on absolutely nothing.So DMM doesn't work, and cold claling doesn't work, SO...

Should be smooth sailing, especially since you have done some trouble shooting already.Best of luck

Most of the time these cant be trouble shooter until you own it.