Hello @noforan thank you for all of this information. My original hunch was that you’ve got a DCDC in your red shrink wrap going somewhere on your daughterboard that you didn’t expect. If you are absolutely certain you’re only feeding power to the system via USB (5VDC), then my hunch is ruled out.
I’m looking into this but to answer your question in the meantime- yes you can. First, please see:
Before anything else, is it possible for you to use a multimeter to test all VCC on the breadboard to verify they are within threshold? You mentioned checking all Notecarrier pins, but could you also check your custom breadboard?
If you are able to quickly swap PCBs, I would give that a shot before testing anything with code, but I’ll leave that up to you. If possible, also swap USB cables and verify your USB port is providing enough power to the Notecard.
I believe your issues may be related so thank you for sharing the other thread. I hope above is enough to get you back up and running, but if not, please follow these instructions to do a trace log and share:
-Tyler