Any help on this would be appreciated.

I posted a thread 3 weeks ago about a problem with my glow plugs and a bad wiring harness. I took the truck into a new mechanic to have him fix the issues and look for anything else that might be wrong. After 15 days I got it back and made it home, but when I checked the work the next day I noticed my gauge in the instrument panel wasn't showing any voltage. No voltage and the truck wouldn't start. I checked the alternator. It had gone bad while at the guy's shop. I got a new one. Then I checked the batteries and they tested good, but once I hooked the posts of each battery to their terminals the negative terminals sparked and each battery went dead instantly. I don't have any power and can't get the batteries to hold a charge after they are hooked to the truck. When I got the truck back, the fuse for my brake lights was blown and the 30A maxi fuse in the power distribution box (#18 for trailer battery feed was blown, too.) The alternator and batteries were fine when I dropped the truck off. Now I can't hold any power. Seems to be a short or bad ground to a novice like me.

 

What did the mechanic do and what was the cost? Need more information.

 

The guy did a few things. Cost was around 400 bucks. I had a GPR put in about 1.5-2 yr ago. New mechanic told me I needed another one while truck was at his shop. Turns out the new GPR was faulty, was 'grounded' right out of the box and so the reason for the arc on the negative terminal of each battery. We're supposed to put a new GPR on tomorrow morning and hopefully this solves the problem.