I don't know if Mav 1.1 -> 2.0 requires a data wipe. 5.7.894 unofficial OTA had a new baseband and radio installed, so that's why I asked if you had flashed it though stock recovery (I had tried this and it failed for me many times). You can apply Mav over 5.6.890, but don't get these updates, at least in 1.1, I didn't look back once I found Liberty and SafeStrapped ICS.
Can you get Mav 1.1 to boot? If so, create a nandroid and TB backup, then do a data, cache, system, and dalvik wipe. Then try flashing 2.0, boot up, and restore apps and whatnot from TB, but if you restore system data, do it selectively as it can cause issues.