Need help same problem!
Nothing helps ..
I was going to flash stock and unroot N7 wifi so i can uppdate to 4.3
But it didnt work and im stuck in fastboot mode.
Reset dosent work
Trying reflashing dosent work
Use nexus toolkit 1.73
tried restore stock kernel and waited 10 min.. but only sais booting downloaded image
Tried unlock (Device where already unlocked) and loc
EDIT: I got it fixed... i reflashed same build 4,2 and it did work
so i tried again to flash 4.3 and got same ****
and finally i did force flash mode and installed 4.3
Ps. i did restart pc and n7 inbetween all steps
Note 3 Stock Love it
Note 2 + Root Love it
Nexus 7 + root (Best Tablet)
S Galaxy Note .RIP