Some other advise (based on spending a lot of time trying to bring this X'Eye to life), one can use a standard Sega CD 2 service manual to fix an X'Eye.. they're very similar (I never found a PDF of the X'Eye). The BIOS is a very cleaver thing. The console detects that no cart is inserted, so it boots the BIOS chip. You can technically burn a game onto the 27C1024, and if no cart is inserted, the game will start.
I believed I used the service manual to trace every one of the 40 pins back to the Sega main processor that sits next to the BIOS and figured out it's standard 27C1024 pinout.