Oops! Flashed wrong bios!

[sevi]

Hey guys. I chipped my mates new xbox which is a v.1.6 with a Duo x2 chip. This chip has two banks for bios' and come pre flashed with an x2 4971 bios and the evox m6 bios for the 1.6. Now I installed the chip and everything went sweet except that for some reason (blaming tiredness cos it was pretty late) I forgot it was a 1.6 and flashed the x2 4981 bios over the m6. Now the box tries to boot three times then frags. Another mate was here at the same time and I installed the same type of chip in his v1.2 xbox. His chip still had the m6 bios on the other bank so I swapped chips, turned on the new box but still no go. I then used the older xbox to flash the m7 bios on one bank of the new chip and put it back into the new xbox but again, after three tries it frags.
Can anyone help? PLEASE!!!!!