I had updated to the lastest 6149 OS after upgrading orginally to the 4189 version when it first came out. At that point, I new that going back to 4189 was possible but difficult.
Anyway, I just had the dreaded 2 flashing red lights after my PB was drained and shutdown. I would not boot after that, just flashed 2 red lights no matter what I did. I had to start all over again and wipe with the BB Desktop Manager. That worked and I am back on the original release.
My question now is, how do I upgrade to 4189 to I can root? I suscribed to the orginal 2.0 beta thread link and now the software update wants to take me to 6149???
you can sign in for OS 2.0 update and install it through Desktop Manager and while it download bar files, replace 6149.92203 bar file with 4869.79475 bar file in Loader Cache folder before it start installing, then Desktop Manager will install 2.0.0.4 in your pb.