Sony will repair any of its handhelds suffering from a broken square button gratis; new models unaffected.
Following complaints by consumers in Japan, Sony Computer Entertainment officially announced that it will repair any PSP suffering from a defective square button. According to reports, a manufacturing defect caused some units" square buttons to stick when pressed and not pop back up. Sony released a statement that said the problem affected only about 0.6 percent of the 510,000 PSPs that were shipped during 2004.
News source: GameSpot