We ended our camping season today

. One last weekend out and the thought of freezing pipes scared us into calling it quits for the year. So we brought it home, unloaded it and took it to my father's home where we applied an air compressor to the city water hookup. Here's the particulars:
1. We made sure the fresh water tank was empty
2. We released the pressure off the hot water tank but did NOT take out the annode (I know, I was supposed to, but learned that a little later in the afternoon)
3. I turned off the "on/off" switch for the hot water heater
4. We then put on the do-hickey thing
Casita gave us to air compress the lines
5. My dad then ran the compressor (always less than 50 lbs psi) while I turn the cold valve then the warm valve in each of the 2 inner faucets, and the outside shower. We then air-compressed the toilet.
Ok, hopefully nothing done majorly wrong there. Then we put 4 gallons of the $4.98 per gallon Prestone in the fresh water tank, and flipped the pump switch. It hummed to life but when I turned the faucet...nothing. We moved the
Casita around so the tank would be in all positions to assure that the level of the pink stuff was where it should be. Nothing.
We then took it to our very helpful/knowledgable friend Leo's house, who informed me that the bypass valve to the hot water tank should be switched so the pink stuff would bypass the tank. Then, he additionally took out the annode and released the water from the tank.
We then tried the pump again to the same result. So we added the last gallon of pink stuff I had, a total of 5, and still nothing. And that brings us now. Any suggestions as to what the issue might be? Thanks!! Oh, and by the water, the pump was working within the past two weeks, and has always worked since we picked it up in June.