AlanDgamerPROXD

I've got an xbox 1.6 to be repaired, but i have already checked a lot of things and i can't find the problem. This xbox was modified to be used as an arcade machine, it used to have a bridge in the HDD's molex conector to the outside of the console, and also it seems all the capacitors had been replaced before. The xbox worked normally for a while, and then it just suddenly stop turning on. I've already checked Q7C2 transistor, the clock capacitor has no leakage, the power button works great and its traces to the Xyclops chip are ok, when i press the button the 3.3V signal goes to 0 (as it should be), but the mother doesn't give the POWON signal, the PSU works great (it gives the POWOK signal to the motherboard, it has no burnt component and when i send a 3.3 signal in the POWON cable, the PSU starts working normally), even i connected a fan to the PSU and it works fine, and when i send the signal, the CPU and GPU heat sinks and the xcalibur chip starts getting warm, but the xbox doesn't turn on. In this state, it gives al the voltages that it should give. I see that some capacitors were replaced with a Sanyo and SMG capacitors, and all seems to be ok, but i know it is not 100% reliable. I don't know what else could i check, maybe i'm forgetting something. Please help