Dell G7 7590 RTX 2070 Max-Q cannot be detect in anywhere.

Hello Everyone,

Hope you all doing well in this year.

I need someone to help me to explain what happening with my laptop.

The issue is one day back to 6th December 2022 I want to play the high-quality graphics game but my laptop running the game very lag, then I tried to take a look in the GeForce Experience to update the driver but it seems to be error. 
Yes after that I go and checked in Device Manager, No RTX showing anymore.

Once I knew the RTX is missing from the windows then I tried to

• Remove all NVIDIA driver (download from Dell Software & Driver page and also Nvidia page) and reinstall the result showing as failed
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• Reinstall Windows OS to latest version & reinstall Nvidia driver the result also showing as failed
• Flash BIOS to the latest version (download from Dell Software & Driver page)
  • In this process, I tried check in the BIOS setting, the Discrete GPU not show up.
  • After checked, I also tried to reinstall the Nvidia driver the result also showing as failed.
• Tried to remove CMOS battery and plug back to reset to BIOS default but the result still the same.
• The BIGGEST part is replace the new motherboard (by technical on-site support) because support team said it might be the problem with the Graphics Card chip, but the result still showing the same. After replace the new one I did all step up above once again and yes the result still showing the same.

The last thing is I have run the Diagnostic Tool on computer start up and found some weird error about video thermistor showing up it say

and the log about the video thermistor showing lowest at -116 c (or lower) and 121 c (or higher)

I'm not sure this error is relate to my issue or not.

I am out of Idea to fix this issue, please someone could help me to share the experience or proper ways to fix this one.

Thank you in advance.