How does one go about shutting down an Apple Store in Manhattan without a computer virus? Just import the Jonas Brothers for a ''secret'' performance. On Aug. 12 the day the band's third album, A Little Bit Longer, went on sale the trio happily obliged. The hour-long set wasn't announced publicly until that morning, and it topped off a week of Jonasmania, highlighted by their guest-hosting stint on TRL, a performance on So You Think You Can Dance, and a Good Morning America concert that drew 15,000 eardrum-busting fans into New York City's Bryant Park. Oh, and one other thing: They sold out Madison Square Garden three nights in a row. The Apple Store spectacle, however, was intimate and a fitting celebration at the end of a day that saw their new album strike No. 1 on both Amazon and iTunes by early morning. (Their first, out-of-print album, meanwhile, now fetches up to $350 on sites like eBay. We're guessing that's approximately four months' worth of the average tween's allowance.) Just 450 fans including a Croc-wearing Harry Connick Jr. and his smitten daughter were let inside free of charge for the 12-song set. And the night's final tune couldn't have been more fitting: Summer anthem ''Burnin' Up'' (yup, Big Rob rapped) brought up the rear as two ambulances outsie treated a slew of fainting gals, who had, predictably, overheated. Perhaps the Brothers need to remind their fans they're just lyrics not words to live by.