Spilled nail polish remover on my keyboard... help!

Best take it to an Apple retailer/service center ASAP and have it checked out and the keyboard replaced if that's all that is damaged.

Sounds like the logic board may also be damaged. If it has been, you're in for an expensive repair of your system. Check with your homeowner's insurance or, if you bought the system with a credit card, any accidental damage coverage your credit card may provide.

Some types of nail polish remover (namely those containing Acetone) can dissolve plastics. Think about how difficult nail polish is to remove and nail polish remover basically dissolves it. It is possible that the remover has damaged some of the keyboard components. There are also lots of internal components that may be damaged by exposure to remover. If you're talking about just a little bit, it may only be your keyboard that has been damaged... if it has actually gotten into your MacBook, you may be looking at more significant damage. The fact that your machine is not turning on is not a good sign.

Be prepared for a possibly big repair bill because this won't be covered under the warranty if yours is still under warranty.