So I found an old xbox for sale at a local shop and thought I'd try jtagging it. Cracked it opened, soldered the cable for LPT-firmware reading. Read the first 2MB of the NAND six times (512MB jasper..), matched every time. Then I checked the CB and its 6723 (kernel 7363).
So I go ahead and flash the nand with "nandpro lpt: -w2 jasper_6723_hack_for_256mb_512mb.bin", unplug it and try to start it for shits and giggles. I get no picture and just a blinking power LED (no DVD attached). I figure that's normal since I didn't solder the JTAG-wires yet. I then go to solder these wires, and try to boot it again, same shit. No picture just a blinking power LED, tried both composite and HDMI. Doesn't seem to be booting at all
Any ideas what could be wrong? I guess the obvious error is that the xbox doesn't like the flashed image, but I can't figure out why. I'll try reflashing it with the backup once I get to borrow my friends monitor . I've checked the board for solder residue/cable crap.