I've done a blind reflash on a TSOP'd motherboard. Not sure whether it works with a chip, but it's worth a try.
You can download EurAsia Pro Generic Flash Disc v1.3, then burn to discs (CD-RW or DVD-R).
Disc 1 is EurAsia, Disc 2 is your custom BIOS. Since your chip now has a hacked BIOS, it SHOULD load the EurAsia flash disc.
Steps:
1. insert EurAsia disc into your xbox, then shut down the console with the disc inside.
2. Boot up xbox with disc in dvd drive
3. EurAsia will open the tray automatically when ready
4. Take out EurAsia disc, and insert BIOS disc & press A
5. Console will shut down when done
6. Power it back up & hope it works.
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If your buddy has an Xecuter 2.6 (or X3) chip installed in his xbox, you can hotswap and reflash.
Steps:
1. Acquire FlashX and view readme.
2. FTP FlashX and your BIOS to the xbox hard drive.
3. Boot up modified xbox and once it reaches the dashboard, remove working chip from LPC pins (leave d0 connected).
4. Install bad chip onto the LPC pins (no d0 wire needed).
5. load FlashX from the APPS menu (or wherever you have it installed)
6. Reflash chip with your BIOS
7. Remove your chip and place his back on the LPC pins
Done.
I'd try the EurAsia method first, walk-through (with someone's help) second, and hotswap as a last resort since you'd need your buddy's xbox to do this.
... if all else fails, mail me the chip and I'll reflash it for you.