Sorry to hear about the water issues. Sounds like you're close to getting the icemaker line shut-off.
If he's handy, I suggest you remove a panel in the storage bay that will give you access to the area behind the UDC where the city water is connected. There's likely a line loose or disconnected behind the UDC. Once determined, then you can figure out a plan of action to get it fixed and get back to camping.
Once, on a new coach, I had a PEX clamp that was not crimped and water leaked badly behind the UDC. I found it fast, crimped it and all was good before any damage was done. Disappointing to be sure but at least it was a simple fix.