@brtcrt: That's a known issue that'll be taken care of automatically in the next NickelMenu/OCP release

.
Right now, you need to uninstall NickelMenu manually. (c.f., the "Uninstall" bullet point in the
NM FAQ.)
(Or do a real factory reset, the one triggered via button/touches during the boot process, as described in the relevant Kobo Support page for your specific device).