If you are an owner of the OnePlus One device, then we have some great news for you. It seems that the first Android 6.0 Marshmallow based custom firmware is now available for the OnePlus One via AOSP ROM.
Keep in mind that this is an experimental build based on the CyanogenMod version 12.1 Kernel, which it is quite stable, unlike other untested builds. In order to install this custom ROM on your OnePlus One device, you will need to install a custom recovery tool such as TWRP or CWM.
Installing Android 6.0 Marshmallow AOSP ROM On OnePlus One
First of all, you will need to download the Android 6.0 AOSP ROM on your device. Then, download and install TWRP Recovery 2.8.6 on your OnePlus One device. After that, download the Android 6.0 AOSParadox ROM zip file on your computer. This file will need to be copied to your OnePlus One device.
To do this, you will need to connect the OnePlus One device to your PC. This can be done via an USB cable, but in order to be 100% sure that it will connect without any issues, make sure that you will install the USB drivers on your computer.
At the same time, the USB Debugging mode must be enabled from your device’s Settings->Developer Options (if the device runs on Android 5.0 or earlier versions) or Settings->Application->Development (if your device runs on Android KitKat).
After copying the Android 6.0 AOSParadox ROM zip file to your OnePlus One device, you will need to reboot it into recovery mode. Here you will need to make a backup of the data you have on your OnePlus One device by selecting Backup & Restore->Backup. When the backup is complete, you will need to manually install the custom ROM on your device.
HINT: Keep in mind that your device must be rooted or it will not work.
Now, return to the main recovery menu and select the “Install” button and choose the Android 6.0 AOSParadox ROM zip file. Once the installation is complete, you will need to reboot your OnePlus One device and let it a few minutes to load the new OS.
HINT: When a device boots for the first time on a new OS, it usually takes a bit more time than usual.