Mike , do you have power to the pump motor or to the relay on the pump motor ?
The reason I ask is a few years back , I had a similar issue with my , HWH levelers, control pad would light up and then die when I pushed any buttons. Traced back to a defective " waterproof " inline fuse holder, corrosion was so bad , the fuse would pass enough power to light up the control pad but wouldn't pass enough power to activate the relay. If you're loosing power when you flip a switch , I'm thinking bad connection in the power wiring.
Picture is of the defective fuse and holder.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.