Low boost PSI

[snailexpress]

If I understood everything right..... you said the positive jumper cable was shorted to the frame.
This can't fry ECM. Set truck fire, yes it can.
Open the battery box and look for black GROUND wires.
One is big going to the starter.
One is about finger in diameter connected to the frame. It is fuseable link. It will burn like a fuse close to the frame end. Hard to notice as wire looks good the link is under shrink tube. You need to pull or twist wire clse to the frame.