Hi my name is Robert..
These types of question can be very difficult without a wiring diagram. Sometimes on the outside you will have a BCC (Battery Control Center) inside that box are some solenoids, breakers, and fuses. DO you happen to see anything like that? IF so let me know the make and model.
You have to have a fuse box on the outside that powers all the items, one thing that catches my attention is the jacks not working, many times they will wire the jacks directly to the battery and sometimes they will use a shortstop style breaker, below is a picture. Some are thermal and some have a small tab that pops out when they trip, as a general rule they like to stick them 18" from the battery and can be on the chassis frame or inside that BCC. You also might have more then one so if you see any I would be checking for voltage on each post. Measure voltage to chassis ground and it should be close on each post. I would also look for any block style plugs, many times they will bundle the 12 volt wiring and use a male and female block plug that plugs together. Sometimes they can vibrate loose or get corroded, something to keep an eye out for, it would be on the harness from the dash to the chassis fuse box. Once you find the fuse box for the chassis I would turn on the ignition and probe each fuse for power.
Also I see this was recently worked on, if it is a good shop they should have kept some type of record on what was repaired so I might see when you had the unit in what they did to get it working....
Another possible problem would be if you had a solenoid for the ignition, if that was the case all the dash power would be out. Not to common to find them but possible if all the dash power is missing...
Please feel free to follow up, if you have a BCC I might be able to assist you more. My goal is for you to be satisfied with my efforts, IF you would like to try another expert please let me know, I only get credit when you select a rating... Robert