When you remove the UIM, check it by the TB. There is a single hole up into it for the EGR tube. Typically it will have cracked there. Filled the LIM with coolant and then filled the cylinders.
Clean up the mess in the LIM (shop vac) and you have two choices. Use 1/4" NPT headless pipe plugs to plug the LIM or install a new UIM and probably a reduced stovepipe etc.
Hopefully no one tried to crank it too much with the cylinders locked up and hurt the piston rod bearings.
One other note is that I've had to attached a piece of vacuum line to a compressor air chuck in order to blow out the cylinders enough to get it to fire back up. If it starts on 3 cylinders..keep it running until the other 3 clear. It really only takes about 3 though.