I have a 2016 Range Rover Sport HSE L494 v6 supercharged with the AJ126 engine i believe. About a two weeks ago I done a coolant drain, flush, and refill. I was not aware of complete headache of bleeding that system. So, during the bleeding process I was revving the engine and then letting it idle and for some reason I had a low voltage warning come up on the dash when I had cut it off for a minute for it to cool down "I had the two front doors open." After I feel good its bleed I leave and head to work, the car hasn't overheated at all even to this day, but half way to work I have no heat at all, so I think I've got a airlock in my heater core. I do all this stuff parking on a hill, raising the coolant bottle, opening all the bleed screws and the bleed plug on the front crossover. Total of 3 bleed screw and the 1 bleed plug. Still not overheating, but still not getting any cabin heat out of any vent, but I was getting no air bubbles out of any bleeds screws. So I decided to buy a vacuum coolant fill kit/pressure tester from the internet and drain all my coolant and start over. Pressure tester held 12 psi for over hour, vacuum held 22hg for 30 minutes and I filled it up and ran it doing a manual bleed on top of it to get any possible chance of air out and still no heat. So this weekend I done a reverse flush of my heater core, and nothing came out really, just the coolant that was in there. Both of my heater core hoses are not hot to the touch. I have a FBH, so my next place I was going to check is the FBH (Fuel Burning Heater) changeover valve because I read on another forum that when that low voltage warning came up it could have caused my changeover valve to stick or "lock out." I pulled up any codes and none where stored the only one I could find where not DTC codes, but some in the modules that where stored. It says intermittent, and I tried to clear them thinking they were old code from when I got that low voltage warning and they went away, but I'm still not getting heat. The codes were B12B9-87 Auxiliary Heater Control Module and B129A-88 Local Interconnection Network Bus D. Ive also tried unplugging the battery and touching the two leads on the battery together and leaving it off for several hours for hard reset and still nothing. I'm not usually just a parts changer, but I'm kinda new to Land Rover and don't know whether its a stubborn air pocket or maybe my ring has swelled on the changeover valve not letting hot coolant into the heater core. Any help, advise, or recommendation would be greatly appreciated.