need help. unable to unroot. now cant turn on

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http://forums.androidcentral.com – i am gonna unroot my nexus 10 i had download the mantaray-jdq39-factory-d79f489e firmware and following the intruction on9 but my device cant get through formatting userdata. the error posted below. anyone can help ? my nexus 10 now cant turn on. only can boot into bootloader. i did tried changing several usb cable and usb ports. this is my bootloader information Quote: (bootloader) variant: wifi-only (bootloader) serialno: R32D102951D (bootloader) version-hardware: 8 (bootloader) version-bootloader: MANTAMD03 (bootloader) secure: yes (bootloader) unlocked: yes (HowTos)