820-3330 liquid damaged, graphic like lines in options wont boot into osx

[nate8organic]

customer sent in a 820-3330 he said he bought it used in 2012 and used it till 2014 when it stopped working right and left it untouched. First thing i noticed was liquid damage and previous repairs. When i test, powers on, in options the hard drive icons have lines slight lines through them, and when loading osx it freezes half way through loading. using the owners drive it loads half way and then restarts with a black screen. liquid is on both sides def see some on the gmux. and on the backside next to the gpu there is components with repair and liquid everywhere. also is on smc. Wondering if i should just start off by running it through the sonic cleaner? or what would you do first? i already tried ram and a pram reset just in case it was something simple. also he said the wifi had bad signal, guessing this might have just been the wifi chip or an antenna but haven't really looked into it yet unless i figure out this graphics issue.
your thought on how i should go about on this one?

 

[dukefawks]

If it hangs during boot the problem will be around the GPU. Probably crap under GPU and/or VRAM or corroded resistor/trace. Have fun with the glue around the VRAM, you'll need to pull and reball them all.

 

[nate8organic]

Okay i went ahead and sonic cleaned it. something to note on this one, i did a pram reset and after the first reset the computer turns off, and every time after that if you press the power button it starts to power on and then just shuts down after about 5 seconds. it does not load back up after the first reset like normal. if i unplug and plug back in it works again. would this issue point to something specific? Thanks for the head up on the vram duke.

also here is a list of all the parts i saw that were previously worked on. R8451, 8452, c8491, c8555, u6100, q8360, u9390, u9330, r9334, u9220, u7760, c4531.
i just wanted to put that out there before i really dive into this one.

 

[dukefawks]

U/S cleaning will not get rid of the corrosion under the VRAM/GPU and GMUX/SMC. Need to flux and heat them, possibly even pull and reball. This board is going to suck,