Things You'll Need
Instructions
Hold down the "Power" button for at least four seconds to turn the DSi off. If the system powers off, hold the Power button to turn the system back on and reset the operating system. The system should no longer be frozen. If the system doesn't power off, go to the next step.
Plug the Nintendo DSi to the power outlet using its AC adapter. Allow the system to charge for two to three hours. A battery may be recharged 500 times or less before being depleted. Once charged, hold down the "Power" button to turn on and reset the operating system. The system should unfreeze itself; if not, follow the next step.
Remove the battery from the Nintendo DSi. Unplug the AC adapter from the DSi. Loosen the two screws with a Philips screwdriver on the battery cover. Remove the cover, then remove the battery. Put the old battery back in or replace it with a new battery. Removing and resituating an old battery will sometimes jolt the system and allow it to unlock itself. Replace the battery cover and retighten the screws. Then, try to hold down the "Power" button to unfreeze the system.