but the spinning wheel of death is most likely due to unetbootin is no longer in trisquels repo's
due to offering to install non-free distros like ubuntu its free software though so if you want to download it you can from there website https://unetbootin.github.io/ also if you feel confident to do so (and i could help) you can compile Freenetbootin from source: https://notabug.org/tomlukeywood/FreeNetBootin