HP Desktop does not wake up properly from sleep after upgrading to Windows 10

I have HP Compaq 6005 Pro Small Form Factor. This machine had a clean Windows 7 install, then upgraded to window 10.

After an upgrade to Windows 10, if I press a key on the keyboard or press the power button after sleep, I hear the fan and hard drive start up, and I’m sure the monitor is receiving a signal but it remains black and does not turn on. Nothing happens when I press a few key combinations like the reboot button. Sometimes my mouse pointer is visible but usually not and it cannot be moved. If I hold down the power button, killing the power supply, and press the power button again, the computer wakes up (not rebooting) to the condition it was before.

I think the computer woke up well a few times and then didn’t wake up again. But maybe my memory is wrong.

I have tried all Windows updates, using HP website for all relevant updates including BIOS, display adapter (graphics card) update, Windows Power Usage Troubleshooter, turning hibernation off and on again in the command line (powercfg/h off and on)

What should i do?