Laptop screen with red tint

So, I have a Dell Inspiron 1564, and recently the screen started showing a red tint all over. It seems unable to display the green color, and icons that should be green such as Spotify are actually yellow or orange. Also, at random times, some reddish dotted lines flicker horizontally across the screen, making me suspect of a faulty screen cable. I ran the following tests:

-The red tint also appears in the BIOS interface, hinting at either a faulty screen/cable or graphics card.

-I replaced the screen cable and the problems persist, so that is out of the question. Now it can only be either the LCD panel or the graphics card.

-I ran the internal tests by pressing the fn key and power up, and something interesting happened: In the initial color test, which displays multiple horizontal and vertical color bars, the green color was not present (it looked yellow again). However, the test then asks you if the colors were correctly displayed. If you select "No", then the test fires full-screen flashes of white, black, red, blue and green color, and in this step, the green color DID appear correctly. So it seems the LCD panel is not at fault, and this would point us towards the graphics card.

-However, I also tried plugging the laptop to an external monitor via the HDMI port, and altough the red dotted lines seemed to persist sometimes, the overall red tint was gone.

So, what the heck is wrong with this laptop? Since the screen showed green in the advanced color test, I think it can only be the graphics card, and very specifically the connector that sends the image to the internal laptop screen. However I don't understand how does the advanced color test bypass that...

I'm quite sure it can only be the graphics card, but I wanted to check it with you guys in case you know something I don't about this. If it is the graphics card basically I need a new laptop :(

Thanks for your time,

Rodrigo