Water damage -- complete tear down and soaking logic board in 91% isopropyl
The screen would flicker black once and a while-- there was liquid damage, I think it was coffee.
I have the tools and have repaired several models of phones so i found the tear down not too difficult and the put together very easy -- I never did an isopropyl alcohol soak before and as it was 91% I left the board on silica gel bags for a week while i was on vacation to let it thoroughly dry.
The laptop's screen currently doesn't show any signs of flickering BUT after the battery hit 100% charge, while the MBA (macbook air) was on the battery will not charge (after getting the charge lower by using the laptop) and when I plug in the AC adapter the screen goes black.
I'm guessing the I/O board needs replacement as it looks pretty bad; I might try and soak the I/O board by itself in rubbing alcohol -- This is a new battery.
As far as advice -- I ALWAYS read the instructions FIRST and then read them again before I get to work. I ALWAYS use clean sheets of paper and scotch tape to draw simple diagrams and label the screws and where they go, for example, I'll draw a patter of circles and their position on the device and name it something simple like "motherboard" -- I don't get artistic, I just work clean and organized. Additionally, I ALWAYS use a very well lit area to work, I often pop out my phone or ask someone to hold a light over me if I need to. I ALWAYS take my time and not force anything -- especially on a project like this that I never attempted. I refer to the photos in the guide, over and over, to make sure I'm not ripping up tabs from the wrong end and I do look at other guides, photos and videos to make sure I know exactly what I'm doing before proceeding.