First thing todo is to get the Enigmah Videomode Switchdisc.
Check around the forums if you do not know where to get it, but please do not ask for it since it is built with the XDK and asking for xdk binaries is against forum rules.
When you got the files burn them to a CD-R/RW or a DVD-R/RW and add a dummy file, 50-100Mb in size called 1.bin or something like that!.
(Use XISO or any other program able to extract and build XIso files)
Boot the xbox with it and Press A (for Pal) or B (for NTSC)
Then reboot the xbox and the video should be back.
If you can ftp to your box, then you could remote execute the enigmah default.xbe, after you ftp it over. Or , if you use Evo-X, make a link to it in the evox.ini so that it is the first item selected when you boot up.
Then just launch it by pressing A.
It pays to read a forum relevant to your problem, the XBMP forum, where THIS
is in the stickys.
Thread moved to the XBMP forum as it have nada todo with XBMC