The OmniROM team has released the first Omni 7.1 Unified Build for OnePlus 3/3T that brings latest Android 7.1.1 Nougat to the device. If you are looking for an alternative to stock OxygenOS for your OnePlus 3/3T, then you might like the OmniROM. This is a unified build, which means the ROM supports both OnePlus 3 and OnePlus 3T, so your device should meet few requirements to install this custom ROM.
Read on to know what are the prerequisites and how to install Omni 7.1 Unified Build on OnePlus 3 and OnePlus 3T. Omni 7.1 Unified Build for OnePlus 3/3T is a nightly build, which means the ROM is a testing version. You might experience some unknown bugs and it cannot be used as a daily driver. Also, you will not get all the features.
About: OmniROM is one of the few developers who build custom ROM for a wide range of Android devices. It is lightweight and said that it is a more secure custom ROM.
Note: Like any custom ROM, Omni 7.1 is also requires latest version of TWRP recovery and root access on your OnePlus 3/3T. If not, check this guide.
Important: As always, backup all your music, photos, data, apps, call logs and SMS/text before flashing.
– Omni 7.1 Unified Build for OnePlus 3/3T requires clean installation, otherwise it will not boot.
– Your OnePlus 3/3T should be running on OxygenOS 4.0.2 (Not Beta). If not, install OxygenOS 4.0.2 [guide], then install TWRP recovery and gain root.
Disclaimer: Please follow this guide at your own risk. We cannot take responsibility for anything that goes wrong. This guide is intended for technically talented users only.
2. Now, boot your phone into TWRP custom recovery and wipe data, cache and factory reset.
4. Once the installation has finished, return to the main menu and reboot your phone.
Enjoy OmniROM 7.1.1 (Android 7.1.1 Nougat). Leave your views in the comment section below. (Source)