OK, thanks, wanted to be sure. But from my experience, once you start the 3DS without an SD card, it always uses the default theme, even if you reinsert the SD, until you select another theme.I'd just recommend to use extdata_tool to backup your extdata before you use a custom theme, then you can remove your sd card and go to Ninjhax 2.0, put your sd back in, and restore the extdata backup if you get a soft brick. Since themes are in the extdata, I don't think you can get an unfixable brick from themes.