PSVita Charging Light Turns On, But That's it?

Hello again. So I recently acquired a PSVita slim in the UK for £11 (it was waterlogged) and I thought why not, because it may be a bit of fun to try and repair.

So the problem is that it shows that it is charging, but will not power on. So, due to a small amount of corrosion on the ribbon cable that connects to the power button, I opted to replace it. In addition to that, I've cleaned the entire console inside and out with 91 per cent isopropyl alcohol and used a multimeter to test the battery which gave back a reading of 3.68V (says 3.7 on the battery.

So I am a bit stuck, I don't know what else to do or check. I cannot boot it into safe mode or get any response from the power button. The corrosion was minimal but there was a small amount on the right board which houses the home button. Specifically the connection to the ribbon cable (the ribbon cable I replaced.

So I have deducted that its either the port of the power button ribbon cable, the screen or the maybe the battery but it seems fine.

Please help if you can, I am at a bit of a loss.