Please help me reviving a 2008 Unibody (aluminum) MacBook!

Hi, I used said product daily from 2008 until 2019-2020. It worked flawlessly.

At some point the MagSafe got screwed and I ended up with the logic board having a short circuit. The computer never turned on again.

I didn't know how bad the situation was at the time, so first I tried a new MagSafe, then I bought and installed a new DC-in board and then, by logic, I realized I would need a new motherboard, so I bought a new one.

Since nobody was willing to repair my computer because "too old yada yada yada", I followed the iFix guide and installed the new motherboard by myself.

Aafter I finished my operation, the computer turned on again -- and it even booted, with the initial sound and everything! However, it displayed NO IMAGE AT ALL. The screen stayed black.

I never got what was wrong and just put my MacBook to sleep in a box for years now.

Flash-forward to this day and I've tried reviving it again. Still not knowing what is wrong, I opened up my MacBook and just in case checked both display data cables, which seem to be well connected to the motherboard. But everything stays the same -- the computer turns on, Apple sound, but no image at all.

I'll say outright that I don't have nor I can't get a MiniDisplay Port-to-HDMI adaptor at the moment. Also, I really want/need to get my old MacBook working properly with no help from external devices.

I've taken some photos trying to make everything look as detailed as possible. Please check the images and tell me what else could be wrong.

https://imgur.com/a/RotjWK3