I don't think this has anything to do with your IMEI number.
Are there any known issues with using the HD2 and HD7 with Android?
When i took my HD2 in for repair, the tech guy said that it was probably running android on the phone and i explained that the phone screen stopped working way before i load it on there and only loaded to see if it was software related. But that got me thinking, if i should even for another HD2 or HD7 and swap over to Android OS. I mean the cost difference is worth going that route, but not if im only going to get short use of the phone.
When I've received the message, I would receive a text message saying that I was blocked and the text would contain a link to a screen similar to what you posted. If I continued to try to tether with a pc browser, it would take the pc to an upsell screen as well.
Well during lunch i narrowed my search to the following phones:
One X === No Replaceable battery
One S === No Replaceable battery
Radar === No Replaceable battery
However, after doing some further testing I realized that after toggling the option "Request Desktop site" in the stock browsers menu, I get that message.
Can some body test out my theory with their galaxy nexus, try to request desktop site and see if you get that same upsell message.
At the moment, you can not flash android on HD7.