Hi,
Soz for delay.
U say the xbox resets twice with a blank screen.
Does the xbox frag? i.e. does the power light flash Red/Green?
If so, then u may have to re-seat the pin header.
Try this & let us know the result.
U will still get error 5 with chip disabled as the hdd will need locking.
We'll deal with that if u cannot get the chip working again.
Regards
Gull