6.0 Starts and immediatley dies.

Okay guys, so I did a head gasket job on a friends 6.0.
Truck received all the HPO updates and got a new HPOP. Still factory ICP and IPR.
Long story short the truck had longer than normal crank times and has now developed a hot no start. Air tested the HPO system and found the passenger side rail to be leaking. Resealed the HPO rail and installed new HPO o rings in the top of the injectors. I air tested again after this and im still getting air leaking on the passenger side but I cannot determine where it is coming from. Is it possible for the injectors to leak on a air test? Also I was using a 9 volt battery to command the IPR shut.

I decided to try and start it and see if I could pinpoint the leak while running,
The truck cranked for a while with the IPR at 85 while cranking as soon as it hit 500 ish PSI it fired, immediately after firing the truck will die like you shut the key off, which it was not doing before. ficm volts are 48.

When the truck starts the ipr drops and goes immediately back to 14, could this just be a bad ipr?

Im going to check fuel pressure tonight, does anyone know off hand if the CTS2 will check cam/crank sync and ficm sync?

Whats the battery voltage while cranking or starting? I've had two trucks crank up and run for a couple seconds and shut right back off and both trucks ended up needing new batteries.