Thank you, Steve. Very helpful indeed. I can probably follow the instructions you gave to do the manual firmware update, but I've read here about several people "bricking" their devices during a firmware update so I'm hesitant. All I really need to do is change my GV credentials. My OBi device works fine, so I don't think I really need to mess with the firmware.
<rant>
I'm appalled at Obihai for doing this -- and for doing it secretively. It's one thing to sell an extended support plan, but it's another thing entirely to turn off functionality and another thing yet to cripple functionality and then sell access back. Portal functionality is fundamental to the device, and telling people a year later that "Oh yeah, that thing you thought you were buying from us was really a rental" is just plain wrong.
This makes me think of those evil people who hijack people's computers with malware and then make them pay a fee to get an unlocking key. (Okay, maybe this isn't quite as bad as that, but this is still pretty nasty.)
</rant>