2005 7600 Instrument Cluster dead after 24V jump start

2 batteries does not equal 24 volt necessarily.
heck most of my trucks have had 4 batteries, would that make it 48V? NO..

Series and parallel. Learn the difference.

 

My money is on some stuff got fried.

Some manufacturers are even advising against jump starting these days due to voltage spikes taking out modules.

 

I would start by disconnecting the batteries for a couple minutes. Re connect them and see what is working. What modules can you see with the scanner? There is a fuse box under the right side dash panel and there may be one under the hood Check all the fuses.

 

Best advice is check some fuses. All of them! Go along with a test light while ignition on and engine running and check for power on each side of each fuse, carefully note the ones that dont exhibit voltage on each end, then when done with the panel testing, go to a service manual listing for the fuses that didn't have voltage, identify the label, circuit they belong to and functions they would contribute to under certain circumstances. Then do your detective work to find out which one got ####ed.