Instructions
Verify that your DSi unit is fully charged by placing it on the charger and leaving it for a couple of hours. If the power will not come on after a charge, the battery may need replacement.
Turn off your Nintendo DSi and turn it on again if a game freezes. Sometimes a simple reset is enough to clear corrupt data or strange behavior.
Remove the Nintendo DS game you are trying to play and use a different game. If the DSi can play one game and not the other, the cartridge may be the problem.
Ensure that the DS cartridge is fully inserted into the game slot. A loose cartridge may freeze or fail to play.