Before ya go opening your N64, it could just be your power supply has gone faulty, why not try borrowing one if you know someone with a N64, or even buy one online like here,
Video Game Accessories | Nintendo 64 | Other N64 Accessories | Nintendo 64 Power Supply / AC Power Cord | 8-Track Shack | Vintage Music, Media, Players, Radios, Video Games, Consoles, 8-Track Tapes, Records, Cassettes,Films & Accessories For Sale and if still doesn't power on you can always ebay it so you're not stuck with two.
(edit: wow...that link looks crazy...lol)
