Daughters' laptop, an ASUS TUF A15 has display problems, mostly the victim of 'fiddling'

The issue started out as a white flickering line at the top of the display. After some research, this is apparently a fairly common problem with the A15, and the solution is apparently to change the display refresh rate. That done, the display was good.
But, continued fiddling in an effort to 'make the display work better' resulted in no display at all on the laptop, and could only get a display on an external monitor via the HDMI porrt.
So, dad to the rescue again - found there were two display drivers installed. Proceeded to uninstall and delete both, which went fine. Windows 10 then used it's default driver, which restored the laptops' own display. Windows then proceeded to replace it's default display driver with whatever it thought was the correct display driver... screen flashed momentarily and then came good again. Looking promising!
But then I decided to see if the fix would survive a restart. It didn't. No display at all again - this time even with the external monitor (and yes, the appropriate Fn-F key is pressed to switch to external display - external monitor reports 'no signal')

It was then that I noticed that ASUS boot up banner / POST / BIOS options were not being displayed on restart or cold boot - just a thin strip of display at the top.

SO, my guess is that the laptop display panel has indeed hardware failed, and that it was only working at a certain refresh rate which was set under Windows, but now that the driver has been replaced, it's trying to display at a refresh rate the panel isn't working with. Likewise, the POST screens also try to display at a refresh rate the panel no longer works with. Would that be a correct assessment of the situation and screen panel replacement is required? Or is there something else that can be tried first, bearing in mind there's no display at all - even with an external monitor - making it impossible to manipulate any settings.