Precision 5540 screen severely glitched

Hello,

I have problem with Precision 5540 (i7-9850H). Internal screen is severely glitched, but external monitor connected via HDMI works fine. Touching upper edge of the screen with mouse cursor, changes glitch pattern on internal display (see attached video). Laptop screen is cloned on connected monitor.

Graphic cards are: Intel UHD Graphics 630 and NVIDIA Quadro T2000.

I reinstalled Windows 10 Pro, but the problem occured again after few days. Installed latest video drivers, but still the same.

I run the LCD BIST described here and it passes: https://www.dell.com/support/kbdoc/en-uk/000134946/how-to-troubleshoot-display-or-video-issues-on-dell-laptop-lcd-panel

When switched off the T2000 in Device Manager the problem still persists.

When switched off the Intel UHD Graphics 630 laptop screen works fine, but not able to get image on external monitor and CPU usage by System process is quite high (15% continuous).

Do you know any solution for that? Thanks!