I finally got my replacement Roamio and was able to transfer the season passes and the recordings from the affected TivoHD without any issues.
As a first step, I plugged in the Roamio and connected it via ethernet to the same network. It took a while to come up and rebooted itself twice to do some updates, etc. I did *not* have to activate it. But once it was up, I could see the TIVO HD as the last option in the My Shows List. From there I could see all the recordings and could transfer the ones I wanted. Unfortunately, you'd have to do them one by one but eventually they all got transferred.
For the season pass, it is very easy. I logged into the TIVO website and under find shows->Season pass manager, it shows both the TIVOs. I selected all the season passes in the TIVO HD and clicked on copy to the other (and selected the Roamio). It was done in 5 minutes.
Just wanted to share this with others who might be in similar situation.