Packard Bell MX-66: screen flickers

Hello,

For some time the screen of my laptop (PBell MX 66) flickers.
The PB tends to diminish after a few dozen minutes.
Would you an idea about the origin of the problem before I resolved to entrust the service of the seller.
Thank you for your contribution.

I think this is a problem of backlight, so very probably VAS.

On an external display, there will also be a flicker?

How do I connect to another screen?