Xbox 360 s v1-2 corona mod

I've modded my Xbox for rgh, I did everything right, but when I wrote xell to nand and then connected the Xbox to my tv and then my monitor I couldn't see anything, the HDMI works fine with other consoles, what did I do wrong? I really have no clue. I also tried to solder the point for rgh again but now it's even worse, when I turn on the console in boots up, the fan stars moving but after a few seconds it stops and turns off. Am I cooked?