3DS XL Screens don't work and speakers pop when turned on

I have a red o3DS XL that was partially water damaged (I have included a picture from the internet with a line drawn where it was in contact with water, and was only in contact for a few seconds before I managed to recover it) and now the screens won't turn on when the power button is pressed and the blue light turned on (and the light used to) stay on and the console would do nothing for minutes on end, but now the speakers give a faint pop and the light turns off after a few seconds. I believe this is because of the many times I have opened and closed it during repair to see if I had resolved the issue due to a microtear on one of the ribbon cables causing the issue.

When I opened the console practically everything was intact and could maybe even be passed as next to new apart from the water damage indicator which had turned pink and a few ribbon cables (the 3DS fell on the side with the 3 most important ribbon cables in the top right, I have great luck) with small traces green/blue corrosion on them which I cleaned off with isopropyl alcohol. I've also removed the top cover for the top LCD and everything there is perfectly fine too.

I watched a video by KyleAwsm on YouTube who had an o3DS XL with the same issue as me and found out that the ribbon cable going to the cameras was the issue and had to be unplugged for the system to work, so I tried that but it didn't work. The other ribbon cable connecting to the speakers and some other stuff when disconnected also didn't resolve the issue, and also completely got rid of the pop when turning on the 3DS, and if I left both unplugged, I still had the same issue but obviously without the pop.

Also, I have turned on the motherboard separate from any other ribbon cables and the power light still turned off.

I would like to make a really, really important note that only a month or so ago one day weeks prior I had reassembled the 3DS and it sat on my desk untouched until I decided to turn it on, and very strangely the back-light for both LCD screens turned on (which made them a light grey but the user interface/any other image was not displayed) along with along with speakers which worked fine and the control buttons worked aswell as the 3DS made the signature jingles when applications such as the camera was selected. Unfortunately me being me I decided to immediately turn it off and disassemble it again in hope of repairing something to make the screens fully work, but however the screens and speakers never ‘turned on’ again. This tells me that both screens are probably fine and very probably a ribbon cable (high chance a ribbon cable) has gone.

I don't have a spare 3DS I can check parts on and I definitely don't want to buy one, and I don't have a tool to check the continuity of the motherboard fuses. Oh and if I didn't mention already, the electronics are dry and there's really nothing to clean apart from some corrosion under the buttons on the motherboard that goes to the ABXY buttons. (By the way, how am I supposed to clean that?) - I have included pictures of both sides of the motherboard and the top LCD insides if anyone can spot something dodgy apart from that.

What configurations of ribbon cables should I have plugged/unplugged which may make the console work or which actual ribbon cables may need replacing?

Sorry for the really long answer, this 3DS XL means the world to me and I really want to repair it to work again, and I will be posting this question on a few other forums so I can collect as many possible solutions as I can.

Thanks for your time!