This has the same effect of flashing
the corresponding factory images, but without the need of wiping the device.
To begin, users should download
the corresponding factory image for their Nexus device, which should be connected to a computer through a USB cable.
Not exact matches
Alternatively, if you don't care about losing any important data, then you can choose to flash the Android 4.3 Jelly Bean
factory image that's
corresponding to your tablet or phone.
Right now, Android 5.1 is available as
factory images for the Nexus 5, Nexus 7 (2012) Wi - Fi model (nakasi / grouper), and the Nexus 10, with
corresponding binaries.