My test environment is Android 4.2 on the sabre-sd board.
Below is my update OTA package steps.
Updating by Android recovery (echo update.zip to /cache/recovery/command)
The update OTA package will reboot automatically after finished.
When I updated Android 4.4 update.zip to my Android 4.2 platform will fail.
But I use the same steps to upgrade 4.4 zip package to 4.4 platform is normal.
Whether there is a different command for different Android version upgrade?