Well, as it turns out, I did contact the previous owner who has been so helpful. Turns out he never used a bypass. He blew out all the lines and put RV anti-freeze in the traps and toilet. So got the water working in kitchen and bathroom. Now, apparently the fresh water level sensor is not working as we have been filling the tank for 20 minutes and it is still showing empty. And one of the two low drain valves is dripping pretty good.
So little by little, we are getting there. Might be able to actually use this RV soon. Lol