Update One Plus One to Android 6.0 Marshmallow via official CM13 custom ROM. As per official blog–
“If you are on CM 12.1 YOG4P or CM 12.1 YOG7D releases, we recommend you stay on course with the SNAPSHOT release channel and not jump to nightlies unless you are willing to accept a dip in quality. Our stable branches are vetted, CTS run and (in some cases) shipped on retail devices – which means the quality of those branches is far and above that of nightlies. We’d advise these folks to stay on the SNAPSHOT train, and we’ll have a quality approved SNAPSHOT for CM13 sometime Jan”.
The guide mentioned below is only for OnePlus One (aka Bacon) and cannot be tried on any other device or variant. You can check device model by going to Settings >> About phone.
We cannot be held liable of any damage done to your device while following the below mentioned procedure.
Install Android 6.0 Marshmallow PAC-man Custom ROM on OnePlus One
Install Android 6.0 Marshmallow Official CM13 Custom ROM on OnePlus One
Take a complete backup of data,apps and settings as the procedure may wipe your data.
Make sure that the battery of device has a minimum charge of 60%.
Enable “USB debugging” on your device by going to Settings >> Developer options >> Enable USB debugging.
ClockworkMod Recovery should be installed.
Download the latest version of ROM from here and Gapps from here.
Extract the zip file to SD-card of your device without extracting.
Switch off device and boot into recovery. Hold power button and volume down button and enter recovery.
Perform a Nandrop backup of your existing ROM. Select “Backup and Restore” and then select “Backup again”.
Select “wipe data/factory reset” and wait till the data gets wiped completely. Click on “Advanced” and wipe off Dalvik cache.
Select “install zip from sdcard” and then select “choose zip from sdcard”. Navigate to “ official CM13 Custom ROM ” file which you have downloaded and confirm to “install”. Wait till it gets installed.
Repeat the procedure to install Google apps by selecting “choose zip from sdcard” and then select “Gapps.zip” and install.
Select “reboot system now”.
You have updated your One Plus One with Android 6.0 Marshmallow official CM13 custom ROM .