Water damaged mid-2010 MBP only boots sometimes

A friend of mine spilled coffee next to her laptop, and some of it seeped into the lower case on the left side through the ports. She said it shut down immediately and she didn't attempt to turn it back on, but brought it to me within half an hour of the spill. I immediately removed the logic board, brushed it thoroughly with isopropyl alcohol, and (carefully) dried it with a heat gun within an hour of the spill, so I think corrosion is minimal.

The laptop will not turn on consistently now—I managed to power it on once by shorting the power pads, and instead of running through some troubleshooting steps, I turned if off to see if I could get it on again (I couldn't—silly me). The computer did boot and the OS loaded.

Where should I start looking for problems? The light on the magsafe adapter glows orange when the battery is plugged in (and the battery status LEDs on the side work fine), and the magsafe connector glows green when I unplug the battery connection to the lobo. The power button on the keyboard is useless, but I don't think the keyboard got wet since the coffee seeped into the case from the bottom.