Plastic unibody MacBook A1342 blank screen with no response

Hi, I recently bought a 2009 plastic MacBook as I was always looking for one of them. It's not the older plastic one, rather the newer unibody A1342. I apologize if this is in the wrong section because the only "MacBook" categories I could find were for what I'm assuming are the Retina MacBook and the old plastic one.

It has no hard drive, so what I'm expecting is the flashing folder icon. Here's what happens when you turn it on.

SIL comes on, it chimes, but instead of a flashing folder all I would get was it fading to a black screen (but with backlight) or in some cases, vertical lines of different widths and colors (mostly various shades of greyscale). Caps lock light would still turn on and the computer would still power off when you hit the power button again.

I've tried booting from an external drive and even used the drive from my other computer (macOS 10.12 Sierra on it). All it would do this time was stay on the screen for about 5 minutes, then the computer would switch off. Pressing the power button does nothing, unless you hold it down for 5 seconds, to which it obviously shuts down. I also tried various commands (e.g. command+option+P+R) with almost no difference, although the commands appeared to work.

I also tried connecting it to an external display and that showed nothing either. I'm doubting it's the display because it ended up with slightly different results every time.

I'm currently thinking it's something with the logic board unfortunately, but it could be something else for all I know.

Please leave any suggestions. Thanks.