Flashing our custom ROM

You have your .zip file and your customized system partition, and you are thrilled to have flashed them to your device.

To flash the system partition, we can use fastboot. First, you must unmount the partition itself using the following command:

~$ umount system_mount_point

Before we start experimenting with the system partition, it's always wise to do a system backup:

"Be prepared. You never know."

Now, you can put the device in Fastboot mode, according to the specific sequence of your device. For our reference device, Google Nexus 6, the sequence is:

1. Power off

2. Press Volume Up, Volume Down, and Power at the same time

3. Release when the Fastboot menu appears

The device is now ready to receive the new system partition. Flash it with the following command:

~ $ fastboot flash system system.img

Your brand new system partition is in place! If your modifications were very extreme and adventurous, you could end up in a bootloop—the system keeps on rebooting and never ends the boot...