Please bear in mind that this product has reached its End of Interactive Support so Intel no longer provides interactive support for this product via telephone, chat or e-mail.
If you have replaced the power supply and chassis, you may try checking through power options in the system BIOS and set all settings in Stay off, for example set "After power failure" - Stay off
You might also test the system out of the chassis, placed on a non-conductive surface like a newspaper, a magazine or something similar, this to check if this related to a grounding issue.
You can also try a BIOS recovery as shown here:
Be sure to disconnect all peripherals not required for the update, even the mouse, keyboard, hard drives and any other CD/DVD ROM, this may take up to 15 minutes even if there is no display on the system
The file that you need to use is posted here: