I guess what I’m saying is, if it was me I would connect it up to a bootable drive (you can just do this via USB) and power it up. This may be wishful thinking on my behalf, but I figure if he had the sound mind to shut it down, unplug it, and not restart it again (plus the knowledge required to remove the hard drive), that he had some idea of what he was doing. But, being human, I assume the first thing your brother-in-law did (besides shutting it down) was to remove the MBP from the coffee spill and soaking up any obvious external signs of coffee with paper towels. If that’s the case there’s a very real chance the MBP will be fine if there wasn’t too much coffee penetration and the spill wasn’t near the worst possible areas (you don’t say where the spill was, or how much of it there was).

Okay, this may seem strange (and many would disagree with me) but based on your question it sounds like the MBP was immediately shutdown after the spill and hasn’t been used at all since for about five months.

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