Update: It only deletes your bootcode.dsi. This can be found in HiyaCFW.7z.
I launched a DSi-exclusive title and it deletes bootcode.dsi. dsi.cfw.guide said that the patches can only be deleted if you update your system, but it turns out it can also happen by trying to play a DSi-exclusive title.
I'm not going to blame anyone who made HiyaCFW, not even Robz8 who made DSiMenu++, but you should never ever try this yourself. It will corrupt or delete bootcode.dsi, and as proof this isn't something else, the Micro-SD card is fine by plugging it into my PC, the adapter is fine, and even the SD-card slot in the DSi is fine. I can load up Flipnote Lennyface and launch boot.nds.
If this happens to you, find the bootcode.dsi in HiyaCFW.7z and replace it.
Last edited by Trash_Bandatcoot,