I installed a Xecuter 3.0 in 2 Xbox (v1.0 & 1.1). Unfortunatelly I made a mistake. I pluged the red X3 reset / eject cable on wrong plug, the plug for Alternate 5V for v1.6. As soon as I plugged the external power cord the xbox turned on without pressing any button. The buttons were unoperative. I plugged off the power cord to turn off the xbox and then connected the right plug on X3 but the xbox didn't power on. I tried without the modchip nothing. I have now 2 xbox with the same problem: they don't boot! (with or without the modchip)! 
PS: A smell came from the front panel! But the problem is on the front panel, the X3 front panel adapter or on the motherboard?
PS: A smell came from the front panel! But the problem is on the front panel, the X3 front panel adapter or on the motherboard?