Basic RV water system......2 water sources (city water hookup via a hose and the on-board pump via fresh water tank)
Water pump sucks out of fresh water tank and discharges into cold water line which feeds the water heater and the hot water lines.
cold water goes in bottom of water heater and hot comes out the top.
Most water heaters have a 'bypass' (connects cold in and hot out) so that water heater can be bypassed when winterizing and/or repairs done.
Some water pumps have a winterizing kit on the suction side of pump....so that a tube can be put inside a bottle of anti-freeze and pumped thru system using the on-board pump
Very few valves in system.
Might be one on pump suction for winterizing kit.....it needs to be OPEN towards fresh water tank and CLOSED towards winterizing kit line
Cold water inlet to water heater tank....needs to be OPEN so water can go into water heater
Bypass between cold/hot needs to be CLOSED so that water heater is not bypassed
Hot water outlet needs to be OPEN so water can flow out of water heater tank (IF YOU HAVE ONE---some systems don't and just have a check valve t stop back flow into tank from hot outlet side)
Water puddling around on-board pump/area......not good could be a crack in pump which would also explain lack of flow
Need to access pump and visually inspect it and the above mentioned valves
ON EDIT:
Just saw your new post......
Open the closest faucet hot side....to expel air and allow time for water heater to fill. That can take some time depending on whether you have 6 or 10 gallon WH. And if pump isn't cracked due to winter freeze.
