Hp Envy 34 All in One won't boot up.

[RByd]

I have a HP Envy 34 all-n-one when the power button is pressed the screen come on in *pc mode states display going to sleep*.

No fan, just an amber power button light. So I have reset the CMOS., but no changes.  Ordered a processor and motherboard.  Guest what?  the same issue!  

Pulled the memory cards and try one at a time, same results

Tested the hard-drive outside of the unit and can see the windows/system files.

Plugged my laptop into the HDMI input port and Display show a perfect picture. I can operate the menu buttons to reset and adjust the screen so it works.

Plugged my laptop into the HDMI output port the cpu fan comes on and Power switch light goes white.?????

After setting for a while the PC will go into a error code mode (2 quick white flashes and 4 amber long flashes) Can't locate any material on this code.  

Can't use a wired keyboard or mouse, because of no power to the usb ports. (can't load a bios or go to a diagnostics screen)

(PC has a wireless keyboard w/dongle)

Thinking that, I may have gotten a bad replacement MB or CPU, but had no way of testing.

Can anyone point me in the right direction or have any Brilliant Troubleshooting Ideals?

[itsmyname]

HP calls those flashes (or tones) "beep codes".

See https://support.hp.com/us-en/search?q=hp%20beep%20codes&filter=-1&origin=pdp

and try to find your model.

P.S. Connecting HDMI-output from your computer to the HDMI-output  port on your laptop is not likely to work, but maybe your laptop has an HDMI-input port?