Dell Inspiron Dead Motherboard?

I haven’t turned on my desktop for a long time. Today plugged in a monitor and keyboard but it won’t boot up.

The machine is a Dell Optiplex 7010.

  • The power supply is firing up
  • power button lights up (but flashes orange)
  • fans spin up
  • USB ports are outputting power (LED on USB hub comes on)
  • I can hear the hard drives.
  • No video output
  • LED on the keyboard does not light up
  • No beeps

Have tried unplugging and replugging all the internal cables. Reseating the RAM. Also replaced the cmos battery.

I read online that flashing orange power button indicates a power supply issue. I swapped in a spare power supply but made no difference.

In response to comment from fred_dot_u I tried to boot without the RAM installed and there is beeping in this case.

Any advice?