YOU ARE RESPONSIBLE SOLELY YOURSELF FOR ANY ACTIONS YOU DO WITH YOUR DEVICE !!!
Please note - I won't explain any single aspect (e.g. how to install 'fastboot' on your PC or troubleshoot USB connectivity issues under Windows). Search the net and consult the search engine of your choice or look here in XDA, there is plenty of information available.
Have fastboot and adb installed on your PC and make sure, you can connect via USB to your device in fastboot mode and via adb
Flash the OxygenOS 9.0.x firmware, which is needed for LineageOS 16.0 - READ THE OP OF THIS THREAD CAREFULLY !
Download the most current .ZIP file of the ROM and place it to your phone's internal memory
OxygenOS 9.x Firmware
Once again: READ THE OP OF THIS THREAD CAREFULLY !
I can't explain it better and I am not going to repeat or summarize this. It really is in your interest to carefully read it - you have been notified and warned.
Please also pay attention to the last section named "Alipay, WeChatpay, Soter and IFAA" - I strongly recommend to use the debloated firmware
Install TWRP recovery
If you come from stock ROM and have just unlocked your boot loader, this is the next thing to do. I recommend to use the TWRP recovery for the OnePlus 3/3T. The following instructions are based on TWRP.
To install TWRP, download the twrp-x.x.x-x-oneplus3.img file (Note: replace "x.x.x-x" in the following instructions with the respective values from the real file name) to your PC, connect the phone via USB to your PC, get it into 'fastboot mode' and enter the following command on your PC:
fastboot flash recovery twrp-x.x.x-x-oneplus3.img
Afterwards, directly boot into 'recovery mode' (enter fastboot reboot on your PC and hold Power and vol.down) - DO NOT boot into the phone's Android system after having flashed TWRP! Once TWRP has been launched, you may decide to reboot your phone and install the ROM at any time later. But the first boot after flashing TWRP must be TWRP in recovery mode.
ONLY perform the steps described here, if you come from Stock ROM or a different Custom ROM!
Boot into recovery mode. In TWRP, choose "Wipe", "Advanced" and spefify "Dalvik", "System", "Cache" and "Data" to be wiped. Make sure NOT to wipe "Internal memory". Swipe to confirm the deletion and get back into the main menu.
DO NOT flash Gapps!
This ROM comes with pre-installed microG. So don't attempt to flash Gapps.
In the TWRP main menu, choose "Install". A file manager appears to let you navigate to your internal memory (path /sdcard). Choose the .ZIP file of our ROM and swipe to flash.
If you update from a previous version of my ROM, including my LineageOS 15.1 build, you don't need to perform a wipe. If you come from a different ROM (or stock firmware), make sure that you have performed the Wipe steps above.
When finished flashing, return to the main menu, choose "Reboot" and then "System", which will cause your phone to boot into Lineage OS 16.0 - be patient, the first boot after flashing a new ROM takes quite long!
Dealing with signed builds
Please note, that this builds is signed with an own key. When you come from a different build, you cannot directly "dirty-flash" this build. You have to perform a "clean flash" (recommended), or - you do this on your own risk - you may try the below steps.
This happens at your own risk - make a backup with TWRP before!
Download and extract the file migration.sh from this archive
This file helps you to migrate from a build signed with the publicly available test keys (i.e. all builds around, which do not state that they are signed). If you come from another signed build (e.g. official LineageOS), you have to adapt the file accordingly (see below links).
boot into TWRP
push the migration.sh file to the directory /data/local on your device and mount the /system partition in TWRP (you can do so using the dedicated TWRP's menu entry)
launch the built-in terminal in TWRP, cd into /data/local, make migration.sh executable (chmod +x) and execute the command ./migration.sh official
(In case you receive an error, try sh ./migration.sh official instead)
If you have a problem, please create a post with these informations:
Original Kernel shipped with this rom:
And try to get log as described here
Please note that I can't and won't support issues with builds using a different kernel or Xposed.
In regards to microG, I will try my best to help when it is related to this ROM (I use it myself), but any questions of the type "the YXZ-app can't do <some sort of fancy xyz Google functionality> properly" are better asked in the respective microG forums.
Graphene OS project
nvertigo67 (for the modded 9.x firmware)
XDA:DevDB Information [ROM][Unofficial][9.0.0][microG][signed]hardened LineageOS 16.0 for Oneplus 3/3T, ROM for the OnePlus 3T
Updated microG from upstream to 0.2.16.204713-10 (picked until 2f29b93)
Updated F-Droid to 1.10-alpha1-212
Please note, that this build is the final LineageOS 16.0 build. - As announced and as some of you may already have seen, I have opened a new thread for the LineageOS 17.1 successor build of this hardened microG ROM:
You can simply "dirty-flash" the "microG" LineageOS 17.1 build over the "microG" build of this thread. I recommend to go this path in the near future.
Of course, I will keep this thread open for a while and answer topics related to this 16.0 build and how to migrate to the 17.1 successor build. I would like to take the opportunity to thank you for your interest in this build and look forward to seeing you in my new 17.1 successor thread.