When I flash my phone back to 4.4.2 it says this C:\adb>fastboot flash zip update.zip
target reported max download size of 1830612992 bytes
sending 'zip' (1482813 KB)...
OKAY [ 54.302s]
(bootloader) signature checking...
FAILED (remote: 12 signature verify fail)
finished. total time: 109.012s
and then thats it. I want to take it back to stock, but it wont let me.