Maintenance mode still boots to the system menu. Recovery mode only boots to the black version screen. The former can be activated with the Wii remote while the latter requires a GC memory card dongle or GC controller in port 4. Both should be exitable by just turning the Wii off. If that's not doing it then it's possible something got screwed up on your console. As Thomas83Lin said if you had Priiloader installed try seeing if you can get into that by holding down reset while you turn the console on. If it works you can try using its menu to get to the system menu.
Are you sure nobody tried to install anything to the NAND or patch anything? Your post history shows messing around with Pimp My Wii, DOP-Mii, ad RiiConnect, all of which can lead to a brick if you do something wrong.