write xell then 3 red lights

[scoobyra]

hi all im new to this i have look around seen simler problems but not the same when i try to write the xell to the xbox to get the cpu key it dose it ok. i then boot the xbox i get no tv signal and after 20 sec three red lights when i write the originall nand back to xbox it boots up and works fine i've tried 4-5 time exactly the same everytime
as anyone got any ideas its an Xenon bored if that helps

 

[manwithoutname]

What's the current dash & CB it has got?

 

[garageinc]

seeing as your new to this have you actually installed the jtag jumper and diodes in? i missed this once in my early attempts after misreading the guides. spent ages pulling my hair out then feeling a right muppet after the penny dropped lol.

 

[Blackhistory4U]

What dash were you running prior to your attempt?