Shorted positive terminal and no crank

have a 07.5 Chevy Silverado 3500 HD with the lmm motor and I had blown the head gasket due to a plastic heater hose connector and drove it for a year before it finally gave up and I had it fixed 5400 bucks later after a 3100 dollar qoute and when I got it back it ran but not like I would have hoped but better than it has ever run. Only problem. Was the key swith was messed up more than it was when I gave it to the. Which I wasn't mad about but after replacing the switch and key cylinder I had to do the theft relearn and it started right up and no problems til the granny clip on the collar blew out and lost all my fluid and I fixed that and I forgot to mention when I got it back the 4 we selector wasn't working but it was driving so I figured fix it later. Then later came I got a clinking noise like hard shift coming from. Transfer case and after replacing a bunch of stuff it ended up being the range fork was worn out so I replace transfer case up and running again and the selector started working after I did the relearn. And now my current issue is engine power reduced and scanner said it was manufactures control which I believe comes from a clean particulate filter and I have had the issue since I bought the truck. BTW I bought it with 300k on it and now it has 375k. So I was miss in the second cat on back since I bought it so I hollow out the one in front a weld new pipe and muffler without other cat and was only able to get one of the 02 sensors back in and the steel tubing I cut off I just connected together with a hose. So it's missing one o2 sensor. So I got the idea to take the inner cooler out and clean it it because it blew the hose off on the driver's side leading into the cooler. I figured it must have been stopped up and so I cleaned it with a kerosene and washed it out with dawn and water and let it dry thoroughly before putting it back together and in the process I took the battery out on the driver's side and so I could get the reservoir out and the positive cable fell over and shorted to the engine for only like 4 or secs before I took it off and re secured it. So I finish up everything and go to start it and everything powers on and will not crank. So I jump solenoid it cranks with no start. I then go to scanner and it powers up with no communication. I check all fuses. With tester then pull every one and do a visual and no blown fuses battery is charged on both sides and still nothing so I disconnect batteries and try a reset still not turning over. So any input would be gratefully appreciated”

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