HP All In one - Power LED blinking 7 times

[2X]

Hello I have the motherboard from an "HP All-in-One - 22-b000nv". I remove the motherboard from the HP PC case in order to put the motherboard in a case that I designed. The power LED blinking 7 times
repetitevely with a small pause. The HDD (is NEW - empty/formated) motor don't start to roll at all and the HDMI out is dead. Original the PC had a screen which connected at the motherboard directly which is the only that is not connected.

[Syntax Error]

Is your startup problem covered by any of these Hp BIOS/HW error codes?

HP Desktop PCs - Computer Does Not Start and Emits an LED or Beep Code : https://support.hp.com/gb-en/document/bph07107

[2X]

It doesn't display bios letters at all.

[Syntax Error]

Is the jumper on the 10 pin feature connector ( above the word '2nd FAN' ) set correctly?

[2X]

The jumper connects the pins 9 & 10.

[2X]

Finally I found that this HP model enebles the HDMI out after the windows loading and this can't changed from the bios.

[ruftas]

There is a cable that runs from the motherboard to the SCREEN. Disconnect it from the Screen. but leave it on the MOTHERBOARD. Assuming you dont need to use the screen. The cable is between webcam port and the WIFI card on my machine.