Wii Backup Disc
The Wii Backup Disc is a service disc apparently used inside Official Nintendo Repair shops to transfer personal data like savegames and console settings between Wiis as part of a repair.
"Change WiiId" is mostly useless. WiiId is only used as your "Wii Number" that you give to your friends so they can send you Wii Mail. When you pick it, it assigns you a new random ID.
It also doesn't boot on full bricked Wiis and it's unlikely that it repairs half bricked Wiis since delete all only deletes savegames/settings and not any channel content (Weather/News/Games..) or IOS.
The "DevCerts" are two WAD files on the disc FS called "dummy-cls.wad" and "dummy-loc.wad," both of which have one content which is 0x40 bytes. One is empty the other one seems to be just random data, possibly a build tag. The "dummy-loc.wad" file also has a certificate chain including the debug certificates. "dummy-cls.wad" has a ticket which the Wii does not accept, therefore it cannot be installed.
While the ID of this disc is 410E or 010E depending on the version, the TMD itself reports it as 1-2, possibly to get extra access.
The Wii Backup Disc was the only known official application to use IOS16. Because IOS16 is signed by Nintendo, and the update partition of the disc only has IOS16 and boot2v2, homebrew install discs were released that used IOS16 and had a copy of the Wii Backup Disc's update partition.
When RVL-CPU-20 consoles were released, IOS16 became one of the only IOSes that could be downgraded without issues, which resulted in general homebrew also installing IOS16 to get access to the signing bug and patch other IOSes.
Nintendo responded in the 4.0 update by releasing a stubbed IOS16 (v512). It is unknown how the Wii Backup Disc worked after this point, although there may have been a new IOS16 released that is v513, or the new disc may have used IOS5.