It couldn't be the screen inverter. All that does is provide high AC voltage to the Cold Cathode Fluorescent Light that illuminates most LCD screens. When there is trouble with the inverter, you just have a dark screen. It would never cause the issues you are seeing there, because it in no way connects to the screen in a way that could cause that.
Corrupt Video Ram could look like that, but typically is expressed over the whole screen. Yes, there are examples of GPU issues that can be selective... but in general you'd see the issue from the BIOS On. In fact, Video Ram issues will persist even when not using your display. Connect an external monitor, and see if you can see those lines. You can even see corrupt Video Ram issues over a remote VNC connection.
What you are showing us is most likely damage to the LCD panel itself. Again, you should eliminate the motherboard as a suspect by testing the external monitor connection first, but those lines on the screen look like separation of the LCD panels from the connection at the very top of the screen. People can encounter these lines sometimes when they have always opened their laptop screen from one corner, constantly putting a twist on the screen. Over time, that twist separates the LCD panel itself from the thin PCB at the back of the screen. It separates in places, and those lines (not that many at first) will typically appear.
Again. I'm not saying that twisting your screen caused this. I'm not even saying that it IS a damaged screen. But corrupt Video Ram, or an overheating GPU doesn't create that type of artifacting. That's why before you go out and spend any money, just do that simple test. Connect an external monitor. If the problem persists on the external monitor, you know you need to replace the motherboard. If the problem does NOT persist on the external monitor, you know it is just the LCD panel itself.