Aeris Elite HELP!

I have had my Aeris Elite AI for over three years and have over 200 dives on it. All was working well. Today changed both batteries in the computer and the AI receiver. I cannot get the receiver and computer to sync. The computer blinks like it does when trying to find the pressure...but it always blinks and reads zero. Have checked all the usual stuff:

Put old battery back in but still does same thing.
Checked the number on the sending unit and made sure the number on the dive computer matches
Took batteries out and reset everything and started over.
Took out sending unit, made sure it was seated properly
Let air flow out of 1st stage hole to make sure port is working properly

Hard to believe the sending unit just all of a sudden went bad while changing the battery, but I am sure that is possible.

Anyone else had this problem? Any suggestions?

Thanks

In case anyone has this same problem...after a lot of tinkering. I took the cap of the sending unit, pulled the spring out a little to provide more tension, then really screwed the cap down. I went about an 1/8th turn more then I felt it needed, and it started to sync up. Seems to be working fine now. Really make sure the screw cap on the sending unit hooked to the first stage is VERY tight.

Thanks for the follow-up. I have an Aeris Elite T-3 and when I end up changing the batteries out (they've lasted two years so far), I will definitely keep your advice in mind.

Jim