How to fix black lines on laptop screen

4] Launch the application > click system tests > click system extensive test tab > click run once > run the tests overnight > the next day click component tests > run all tests [some are interactive > post images of the test results into the thread
NO!!!!! [see directly above]

5] Open HP.com > support > software and drivers > enter the product or serial number or model > select the operating system > view drivers > download and install HP support assistant and if available download and install HP softpaq download manager > run softpaq download manager after support assistant > update drivers and BIOS
ALL drivers and BIOS updated and current

6] perform windows updates
ALL Windows Updates are current!

7] open device manager > click view > show hidden devices > manually expand all rows > look for any row displaying a yellow triangle with black exclamation mark or unknown device > post images into thread
Good idea! Just now did that [only for-me-useful suggestion so far].
No warning triangles

8] in case there are problems performing any of the above steps > place the computer in safe mode > report the change if any using safe mode
Boot into Safe Mode on Windows 10
Already did that