Do you have an alternative to OSFMount? My version of Windows doesn't play nicely with it. Meanwhile, I tried No$gba (with the modified ulaunch nand) and I get greeting with the ulaunch splash then the black screen of death (an error has occured and power off your console)
EDIT to previous post: it seems that the Homebrew entry point doesn't work, after 122 taps, erase and paste, the system freezes. I will check if there's a problem with the boot.nds file (unlikely)
Edit2: Entry point is working.
Edit2: restored the unmodified nand to my DSi XL, tried opening the nand and saving it through Tempnand (as you suggested earlier), booted to hbmenu to install unlaunch, still stuck on the "FAT" loading.