To help avoid future need to unclog the spout, I have always pressed down on the kcup with my fingers after inserting it in the holder. What this does is it releases the vacuum downward. If you don't do that and close the lid, the coffee or whatever is in your kcup, shoots upward. Then when water hits it, some comes out but some will stay and clog it.
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.