@droftarts I fixed the channel assignments and disconnected heater 1. System still went into reset and looked like a short because all the PCB LEDs blank out the moment I select either T0 or H1 (GUI links), or send T0 by the console.
However, the heaters are working now and I've tuned them up already.
I tried a few more times with T0 or T1 though and haven't been able to force a reset. It would be great if it stayed this way!