If you are on liberty 2.0, then you are still on 2.2 and are rooted.
So then, there's a pre-rooted gb rom available, the OP on the MDW forums by p3droid has links & instructions on how to flash it correctly. You (assuming the above 2.2 & root) do not need to sbf, or do anything other than booting into recovery, making backups, wiping both data and cache, then flashing the zip from the sdcard
DX bootstrap recovery will work to get you on to gb, D2 bootstrap recovery will work in gb (DX version does too if you change the usb options) if you want to go back to 2.2 BUT you will need to sbf as the firmware is diff.
Liberty is not going to work on gb, that version is a bit of a ways off.
There are a few rom's already (almost?) for gb, but expect to stay stock for the time being.
I strongly encourage you to read through the instructions before making any attempts, and the OP is updated regularly but it can't hurt to read a bit of the thread as well
I gather you're a little new to some of this, if so READ thoroughly any threads/advice before venturing out too far ahead. My experience has been that most issues or failed _____ have been due to people making simple mistakes. I've never had a serious problem I couldn't recover from quickly, and have never needed a computer to root, rom, theme etc... you just need to fully understand the steps and process before starting
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