Xbox shuts down then frags

Ok I have an xbox i was trying to find out what chip I had in it so I could figure out how to tuen it of while doing so i unconnected te wire connected to the d0 point. It was soldered to the top side of the mobo. Well i tried soldering it to the bottom one. Now when I turn it on it turns on then off does that 3 times maes a noise in the dvd rom or hdd i think then it frags. Does any1 know why? I did search google.