Detroit:
That's not your fault, it's a bug with the FlashBIOS (Cromwell). I've seen this identical behavior on ALL XBOXes that I've modded with Xecuter 2.2 Lite chips (preflashed with the FlashBIOS Cromwell). It can take MANY reboots to get Cromwell to finally post video. It's like the XBOX has to hit a certain temperature before Cromwell decides to work. P.O.S. In order to reduce the number of reboots, it helps to flip the switches on the Xecuter chip, switch memory banks, and turn protecct/unprotect off/on a few times. If you get a black screen, let it sit that way for a few minutes, then try again. Once you get video and as long as you don't shut down your XBOX for too long after that, you should continue to boot into Cromwell without issues. Leave your XBOX powered off for more than a few minutes and you're f**ked again.
Cromwell is a useless piece of shit, my goal with any modchip is to quickly wipe the factory-installed Cromwell, either replacing with a newer version or some other BIOS....

Tips for creating your "BIOS Update CD"....do NOT burn an "ISO image", burn a STANDARD data CD-RW at 2x or slower, and fluff it up with a few .zip files, preferably making your disc 20MB or larger. Just rename your BIOS to bios.bin or any of the other acceptable BIOS names, and the FlashBIOS should work like a charm (if the damn thing posts video, of course, which may take a few dozen reboots). Make SURE you use x2bm to create a 1MB BIOS image, import the SAME BIOS into all 4 banks, then save. Once you have a 1MB BIOS file, you should be good to go with burning it to CD-RW. As for media, I've found Sony CD-RW to be the most "versatile" in the Phillips and Thompson DVD drives, which are picky about reading CD-R and some brands of CD-RW. The Samsung DVD drive doesn't give a shit, it'll read anything circular, you could probably cut a piece of bread into a circle and stick it into a Samsung DVD drive...it would still find a way to read data from it...