u know before his guide although it didnt update firmware i was able to use the ota modified to flash in twrp and it upgraded me to stock unrooted b140 just firmware was still b130 wish i made a backup of it the b140 for those people who wanted it xd then i would of had b130 stock b140 stock and the b150 stock no root xdMy first time trying to update I didn't swipe the allow system modification (Kept it read only) but I did mount System, Cust, and Data. Second time I did swipe and triple checked they where mounted. Third time TWRP started restarting my phone over and over and over. So I had to shut down and reload it up and flash again. The last time I wiped everything so I wouldn't have a system, cust or data and that seemed to be the trick getting it to update from b140 to b150.
