Do not download random firmware files from websites. The risk of bricking your DSi is extremely high, and there is no official PC-based installer. Use game cartridge updates or leave the firmware as-is.
An SD card (Standard SD or MicroSD with an adapter, ideally 32GB or smaller, formatted to FAT32). A computer with an SD card reader. Step 1: The Memory Pit Exploit Nintendo Dsi Firmware Download
TWiLight Menu++ acts as a custom operating system interface that lets you launch games and apps. Do not download random firmware files from websites
