Hi, I happened to read your issue today. It's pretty disappointing to see your beloved Mac under such an undesirable mishaps. But, of course there's a way.
First of all, you need to be very careful here. (What the heck since the liquid spill has already taken over your DC-in board). Still we have some amazing chances left since I've come across such fate and have corrected (fortunately) and hope that fate is positive in this case as well.
What are you doing now? Okay, since the board has a strong power lines, and the liquid spill is over it, I can imagine the polarity tension of circuit current flow within. Besides, you are not going to fry it with STATIC OVERFLOW. Hence I assume that you have discharged all your STATIC from your body if you are not equipped with STATIC REQUIREMENTS.
Long story short, touch a metal object with both of your hands and feet to discharge the STATIC if any with you from head to toe.
Now, get a little pure alcohol dipped over microfiber and rub the entire DC-IN board gently and wiping the spill and its effect (disgusting color and odor) completely away. Just be worry that you are not nocking off any tiny transistors. And for sure you are not using any metal while cleaning. Use finger (using finger in this case is very positive). Clean it well both over to the surface and to the reverse side as well. Clean very well.
Don't use hairdryer. The alcohol gives off itself in few minutes.
Now clean the same way over the house where the board houses. I can imagine how nicely you have already cleaned the ports.
Now, another sensitive part. Clean the cable slots fairly well leaving no tress of spill and make it as shiny as it can be.
If any spill leftover is noticed around, also give a close look or even use the magnifying glass to wipe that out for good.
Now your job is done. I believe that you are also one of the luckiest people I met who fortunately didn't fry the entire board but just impaired it partially. Not a big deal, you can always replace it. But for now, I hope, this must have helped if you have not done it yourself by this moment I’m writing.
Cheers!