Computer not responding to keyboard

[robert1_vaz]

Good day

I Have a HP EliteDesk 800 G1SFF   PC , it was not been used for a while(2 Years),   today i tried to start it but it fail to start.

Major Issue is the motherboard is not responding/Detecting   Keyboard.

upon start i get the following message, the message say to press F1 or Esc but the keyboard does not respond 

Below is the message i receive on my screen 

_________________________________________________________________

Default setting Loaded

161- Real-Time Clock power loss 

F1: Boot           Press Esc key for startup menu  

-------------------------------------------------------------------------------------------

I tried pressing F1 and Escape but no response 

Following troubleshooting carried out but no success

1. Hard reset (holding power button down for more then 10 sec with power cable disconnected)

2. Removed the battery from the motherboard and refitted (Battery tested and found to supply 3 V).

3. Removed all hardware and tried to restart.

4. Tried to use a PS/2 type Keyboard (Working keyboard tested on other computer) 

5. Tried a brand new Keyboard (Working keyboard tested on other computer)

6. Tried using different USB port.

7. Tried cleaning the USB contact 

8. Removed RAM cleaned contact and refitted it

Also please note that when the key board is connected the  Caps, scroll lock and Num Lock does not come on when the respective key are press.

When the computer is started with the keyboard connected, upon start the keyboard lights(Caps, scroll lock and Num Lock) flashes but later the keyboard will not respond after the message on the screen is displayed 

Please an some one assist 

I also tried cleaning all the interior parts but with no success