Default Please Help me Fastboot AC

hi guys my friend gave me this one x with one problem, phone is rooted. The issue is there is no OS on the phone. It will only boot into TWRP. he accidentally deleted everything and now I cannot get a rom copied back to it. When plugged up to a PC via USB, I always get "Unknown device" error from PC. Tried ADB but cannot get the phone to go to Fastboot USB

Bootloader says Fastboot AC look the pictures
Thank u very much for ur help
[IMG][/IMG]