2007 MacBook Pro screen flickering, not constant

My screen is sometimes dimming ever so slightly. I recently had to buy yet another charger - this one I bought from Apple so it's legit (cords always weakened on others).

Also bottom of the screen sometimes looks as if there are tiny headlights dimmed pointing upwards. Other times it's fine, entire screen is balanced w light.

Outside on the case where the charger portal is there is some black scarring as if burned. Wondering if this needs to be replaced? or is the screen going? I've replaced the hard drive 3 times, the Nvidia GPU chip was faulty, that was done years ago, and the DVD drive. Nothing else

Any suggestions? or something I can test to see what's wrong?