chill bro, i had the same problem, i unplugged all my drives except floppy and xbox 360, here was my proccess when i was in your shoes, i TEMPORARLY had the dvd drive plugged into xbox 360 but no SATA to the 360 mainboard, that let me boot up. But To solve the bad flash, i made sure everything was cool on the computer, made sure i was injecting everything write, i mean what it had to do with my marriage code, then i went to MTKFLASH and i did the sequnce, before i hit enter to enter the command "mtkflash w /m hack.bin" i turned on the 360, and waited 1 second, then hit enter, then hit 1 when it prompted, then it recovered with the new flash, and everything worked, because MTKFLASH messed up while i was trying to get it to work. I hope this helps.
EDIT: while i was reflashing to the hacked xtreme firmware, i renamed it ORIG.bin, just make sure to not confuse yourself. I jus did it for my own confusing sake. But now my 360 is all good.