If none of these suggestions work, take the feed line off the pump. There is a small hole in the middle of that connection on the pump side. Stick a skinny allen wrench in there and see if you can push the valve up and down. If it feels solid, that valve is stuck. You will then have to remove the nut (7/8 socket I think) and take the valve and spring out and clean it and lube it up with some ps fluid and reinstall.
If it is stuck then this may not help it much as the pump may already be burnt up from running it.