Yes it's frustrating. I had a KZ with Norcold. I spent hours troubleshooting. New control board. It ended up being the optical sensor ( the push pads to change setting).
Section 3 has some quick troubleshooting tips. Page 73 has the info on how to access the on board diagnostics. I took couple on my dis mode. I would check the breaker at main distribution flip off then back on.
Three major inputs to system. 1) DC for control board only. 2) AC power within acceptable range. 3) LP with 11 in w.c.
In pic I am on step 4 , stored error message is failed to light. DC volts to low, and door open for more than 2 mins. Mine is working. I know these are true based on events of how I went through startup.
Doug & Tiffany
2016 F-350 Platinum DRW
2010 Harley Davidson FLHTK (Ultra Limited)
2015 Voltage 3605