Truck won't start, not the fuel pump

A few months back I had a camper installed which included a dome light. I don't know why they had to do anything with moving the battery but the bracket that holds it in place was not properly readjusted and eventually gave way causing the battery to slip and the chassis ground cable to tear. I noticed it when I couldn't start the truck and opened the hood. Replaced the cable and still nothing. Replaced the battery (after verifying it was bad at the auto parts store. Still nothing. It cranks and cranks but doesn't engage. Had it towed to the shop and they said it wasn't the fuel pump that maybe it was the alarm because they were able to get it started. FAiled again, I replaced the fuel pump relay and the spark plugs to no avail. Took it to another shop, they said it was the FUEL PUMP, they replaced it with the filter and the relay (I had already replaced the relay) and charged me $1280 w/2yr warranty, etc. Well it failed there at the shop when I went to pick it up. They took it back inside and "reset" the anti-theft system and it started (that's what they said). Worked for 3 days. Now I'm stuck again at work with the same exact symptom= cranks, but will not engage and startup. Please help!

 

does it have a aftermarket alarm in it?
if so i bet the immobilizer is freaking out and not letting the truck start