I am having a similar problem with a Dell 5150. The power light blinks slowly amber when I try to turn it on. I checked the power supply, out of the machine, and when I grounded the green wire which is pin 4 sometimes labeled P_ON everything worked as it should. When I reinstalled the power supply and shouted the P_ON wire the machine started up fine. I had to put the machine back into service so I didn't have time to do anymore testing, but the machine would not start when I brought it back out to the production floor so I had to jump the green wire again to start it.
Sorry but I'm not. There must be lots of us. For me cadman stands for Cadillac man built for comfort not for speed thats me.