i have recently had the issue wiht the new 621 update locking me out of root and not being able to do what i want for my phone i have worked for 2 days on this now i found i could get a file called dx 621 root i had to make a machine i had inot a umbuto machine using linix and coded it like this from terminal
typed :: chmod +x sbf_flash "enter"
plug in phone
type:: sudo ./sbf_flash mb809-2.3.5.sbf "enter"
this sbf file is in the dx file must copy file wiht sbf_flash to home directory befor attempting so far i can now root my phone and seems to wrk so far i have now tried one rom to no avail i got stuck and had to do this all over again as i get batter i will try it more phoen was going dead so had to put on charger but i also had to download a bootloader to get it to load the new boot file to install hard to fine some of these things any questions as i am a newbie at all this i have only done this like 3 times for my phones but learning as i go here i forgot to metion the rom i was trying to install that locked it in bootloader was liberty now sure why yet or if anyone else willl have the same issue but working on it