Recovery Mode

The recovery mode (also known as Safe Mode Boot) can be accessed when turning on the Nintendo 3DS while holding A+R+L+Up(DPad). This menu is made to update your Nintendo 3DS through internet, if an update previously failed.

However it is possible to use this menu to delete the nagging update message if your console downloaded an update while in sleep mode. It is believed that this menu simply erases all update data, as it should normally be accessed when the update files are corrupted.