I would check the positions of the HOT WATER HEATER BYPASS values...
If these are still in BYPASS mode then water will not fill up inside the heater to be heated. This may also destroy your elements inside the heater if it is fired up without water in it.
I thought I had diagrams handy for one value and two valve model bypass valves positions.
The clue might be is when you opened the relief value. It should spray a whole bunch if the water heater has water in it and pressured up.