The xbox360 had the dashboard 2.0.12611 once ran the Brotherhood Assassins Cred appeared Status Code 23ef-3080-B200-0700-c000-0013.
I upgraded to 2.0.12614 dashboard and completed by pen drive. But do not read the original or backup games. I used the Russian method (no need to drill the CHIP MXIC) and use the USB360 Pro to write the 1.91 FW, but when I try to write the original FW "authorization failed" and "verification failure".
Again, what is 2.0.12614? You made up this number, I'm fairly sure. And are you using a PMT cable?
Also, for testing purposes, try to use an older game. Assassin's Creed: Brotherhood is an AP 2.5 title, so that's an additional complication if you're using that disc to test with.