The water coming out the hose inlet accounts for the "no pressure" .. there is valve in there operated by a springy thing which is stuck open - you might get lucky and reset with small screwdriver or even attaching hose and turning on water for second or two .. not expensive or difficult to replace.
This happened to me. While boon docking, I wondered what that capped inlet was for and opened it. The pump blew a rubber piece and a lot of water out before I shut it off. We never use the city water connection, so I just put the cap back on and left it with no check valve.
