In a frozen state, the Nintendo DSi remains unusable. A frozen Nintendo DSi will not respond to commands, remains stuck on a specific screen and sometimes will not power off or on. The console will freeze due to a problem with the battery or an issue with the operating system. You can fix a frozen screen yourself, but if the problem persists, contact Nintendo's repair department for further assistance.
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.
Order a new DSi battery from Nintendo. Place tape over the contacts of the old battery, then recycle it at a proper collection site.