Hp Elitebook 840 G6 intermittent erratic display issues

[Pieter_ZA]

Good day I have a customer with a fairly new Hp Elitebook 840 G6, bought April 2020. It gives intermittent erratic display issues. The display (internal and External) either gets color lines all over or color blinking blocks all over. Now that I want to start it up it just stuck on startup screen "Protected by HP Sure Start". I can't even go into bios.  

[WAWood]

@Pieter_ZA 

You have two serious, different issues.

As to the first, whenever display artifacts appear on both the laptop screen and external monitor, that is a clear indication that the video chip on the PC is failing, and since that is soldered to the system board, it is not replaceable.

As to the second, HP Sure Start is a BIOS protection scheme.  To get around it, keep tapping F10 key (A few HP products use F2 or F8.) just after you power up your HP laptop (At this point the screen is still black.) Soon you can see the BIOS setup utility. Step 3: On the pop-up light blue window, disable Secure Boot and then enable Legacy Support using arrow keys and Enter key.

IF this does not work, then you are stuck and will need the BIOS password from the customer to get further.