Adding the NVME causes boot loop?

[hmuller]

Any idea what a symptom of drawing too much power could be? I don't know much about that side of things but looping in boot seems odd.

That the computer doesn't have enough power to run?  Maybe that's why it won't boot?

My gut tells me zaius has identified the source of your boot loop problem.

I have a USB 3.0 external hardrive that I can attach and use after the PBP has started. But if I plug it into the PBP then start the PBP, then it goes into a boot loop too. The external hard drive draws too much power when starting to allow the PBP to boot properly (even when the PBP is attached to the external power source), I expect the same occurs with your NVMe drive. It is probably drawing too much power while the PBP is trying to boot.