Laptop screen shows stripes?

Following problem:

For a while now, my screen has only been showing vertical stripes and I would now like to dedicate myself to that. The operating system starts up as usual, you can hear the system tones, but you can't see them. Unfortunately, I no longer have a guarantee - but I need the laptop because as a student I have a hard time finding a new one.

My first obvious thought was that the screen has one broken. However, this was quickly checked using my brother's laptop (same model). There the screen attached to the other mainboard worked without any problems, so this and the inverter board can be excluded.

My second thought was the graphics chip. Quickly checked with a second screen - this works without any problems

In my opinion, it should be due to the connection of the mainboard to the screen or the socket.

is there still a way to save the laptop? Is my suspicion correct or it could be something else. Or what exactly.

Thank you for all your answers, I hope you can help me

In my opinion, it should be due to the connection of the mainboard to the screen or the socket.

I also consider that to be the most likely cause. Whereby the connection is usually the plug connection, but also everything else on the way between the graphics chip and the monitor (soldering points, conductor tracks).

is there still a way to save the laptop?

I would open it and check the connection, starting with the connector. If you are not familiar with electronics, a repair shop might be a better solution than getting involved yourself.