Like Bob said the easiest thing it could be would be the check valve right by that zones shut off valve handle. A tap with a light hammer will usually start the zone if that was the issue. They have been known to stick and I have had that issue occur once.
For troubleshooting one has to believe that the thermostat is OK given there is one fan response in the zone, all of pumps and fans are triggered by the same thermostat contact through a relay or otherwise. I would look at the high low off switch in the living area for the fan that is not running, it may have been inadvertently switched off.
If you open up the door to the Aqua Hot bay with the burner off, then turn on the bedroom zone that works and listen for the circulator pump, you should hear it. Then turn that zone off and turn on the living room zone and see if you hear that pump. If you do it is blocked or air bound if no heat is present. If air bound you can pull the hose from the overflow tank and back feed air through that tube using a compressor and an air gun that seals well to the hose diameter. Set it on maybe 10 lbs of air and pulse it a few times. I did not think that technique would work but it did after I drained down a zone for repairs. Roger shared that procedure with me.
If you don't hear the pump then you would need to measure that the pump has voltage going to it or not to determine if it is the pump or the control circuit. There are 12v fuses for my configuration and there should be for yours. Could possibly be a fuse, hopefully not the circuit board. If it was easy enough to switch the wires to the pumps from the bedroom to the living room pump that would also be a way to know if the living room zone pump works. Hope this helps.
Later Ed
