If you have already unlocked your bootloader, rooted, and installed a custom rom to your New Nexus 7 2013 you may find it difficult to accept updates. The easiest way to update your device is to install a stock rom if you are currently running a custom rom. Scott of Scott's Roms, famous for his Clean Rom series, has put together a Stock Prerooted rom of the latest build for the Flo Nexus 7 2013! Simply download the rom from the source link below and flash it over any other firmware. It doesn't get easier than this folks.
Via Scott'sRoms
Via Scott'sRoms