I just replaced the power connecter also.
Since the system hadn't been used a very long time nobody could remember the password to log on to windows.
So I reboot the viao and tapping F10. I get into the system restore, and see the option to do data recovery. So I do data recovery. I use an external hard drive plugged into the USB port, all seems fine.
Next I boot it up and start windows. Windows comes up just fine. Next I try to find some password recovery (on another computer). I find something and "burn" the iso to a thumb drive.
After I burn the ISO password recovery tool to the thumb drive I put the thumb drive into the Viao and I get power on, hd spin up, display turns on, but no boot up. No "VIAO" on screen, nothing, stuck just like everyone else.
So into the board I go, I have everything off the board. One by one I unplug every attachment, press power button, still nothing. And of course I finally find what is killing the board. As it turns out it is the web cam connector. It's right next to the display connector and very easily slides out, it doesn't pop in like most of the other connectors.
Next I try to boot up with the USB password recovery tool and the very same problem. Power light, HD Spin, CPU Fan, and display all on, just "nobody home". Unplug the thumb drive and viola, up she boots.
All in all I suspect that the USB controller is overloading the MB during boot. I have a usb mouse after boot working fine. With the data backed up to the external HD, now just restoring the system.