OnePlus has officially updated Oneplus 3 to Android 7.0 Nougat.If you haven’t update yet then check out our detailed guide [icon name=”hand-o-right” class=”” unprefixed_class=””] How To Install OxygenOS Open Beta 8 On OnePlus 3[icon name=”external-link” class=”” unprefixed_class=””].As the Nougat update is in beta version there are few bugs present in the built.Many users are reporting the bugs.So if you want a stable built then you should use the marshmallow firmware.Follow the given guide to easily Downgrade OnePlus 3 to Android Marshmallow From Android Nougat. If you have already updated your OnePlus 3 to Android Nougat and want to Downgrade OnePlus 3 to Android Marshmallow From Android Nougat, then this is the right place for you.Thanks to Senior XDA member Mina Mngawy, now you can easily Downgrade OnePlus 3 from Open beta 8 to OxygenOS 3.2.8 (Android Marshmallow 6.0)
DISCLAIMER
RootMyGalaxy.net is not responsible for any hardware/software issues that occur to your device(s) by following this guide. We are certain that the following guide is carefully written, avoiding any mistakes on our side. If you are unsure of the causalities that may occur if the procedure goes wrong, then please don’t proceed.
PRE-REQUISITES
This guide is for OnePlus 3 only. A complete nandroid backup of your device is recommended, in case something goes wrong.Guide How To Create &Restore Nandroid Backup On Android Devices Make sure your device is charged at least upto 60%, to prevent unexpected shutdowns in the process. Before you begin with the tutorial, make sure that ‘OEM Unlocking‘ is enabled from Settings > Developer Options.
Note: You can Contact OnePlus Customer Support, to Downgrade OnePlus 3 to Android Marshmallow From Nougat officially
Downloads
Download OxygenOS Full Zip file Download Modified TWRP for OnePlus 3 Download Stock Recovery of Oneplus 3
HOW TO Downgrade OnePlus 3 to Android Marshmallow From Android Nougat
First, download the Modified TWRP for OnePlus 3 from the download section above and flash it via recovery. Next, reboot your Oneplus 3 into Recovery mode.
(If it asks for a password then skip it and allow modifications on the system)
Then go to Mount and mount system. (recovery menu) Now go to wipe section and change the file system to EXT 4.
(To do so go to Wipe -> Advanced wipe -> select system -> Repair or Change File System -> Change File System -> EXT4)
Then go back to wipe section and Format Data.Do a Factory Reset again.Once done, reboot device to recovery Transfer the OxygenOS 3.2.8 zip to your device over MTP. (Staying in TWRP recovery) Now install the ROM zip file from the TWRP’s install section Once the installation is done, reboot OP3 to bootloader mode. Now download stock recovery from the download section above and place it in Fastboot folder and rename it to recovery.img Now flash the stock recovery by issuing the following command
Now reboot your device into recovery and do a factory reset your phone and reboot. Done! Now your OnePlus 3 should be on Android Marshmallow
If you have any questions related to this post, feel free to comment below. Source
