Ok...Mine had similar issues. After trying all of these I was still unable to get water to flow. So, I took the head apart. I then removed the hose from the nozzle that is in the head. I started to brewer, carefully holding the hose in a cup. I got some water flow, but not much. I then took the nozzle out of the head and blew through it. Apparently it is a pressure sensitive nozzle and it may have been stuck as I was able to clear it out. I ran the cycle through the brewer several more time before I was able to get good flow through the hose. I then hooked it back up to the nozzle and it works. I just made a fresh pot...good to have you back Keurig.
Be careful with the hose when brewing as the water is very hot.
The burping method may have had the most impact as I would have the machine on and tilt it upside down (water reservoir removed) and I could get some flow.