degen Like super usable vs totally unusable after a while. I'm not sure anymore if I tested the version you're on now.
If you need some help, let me know. Basically you unlock the bootloader somewhere in the Android Settings. It's a simple switch. Then you get the latest TWRP image from twrp.me for the OnePlus 3. You reboot into fastboot mode, and then from a terminal on your computer, type fastboot devices to see if the phone is connected properly. If it shows up, type fastboot flash recovery twrp.img (or whatever the filename is). Then reboot into recovery mode, which is now TWRP. It automatically runs ADB in the background. So you download Paranoid Android 7.3.1 for OP3 as a zip file and then copy it onto the device by typing "adb push paranoid.zip /sdcard". Then the file is on the phone's internal 64 GB memory. You can then install the ROM from within TWRP.
If something ever goes wrong, dont worry for there is an unbrick tool: https://forum.xda-developers.com/oneplus-3/how-to/guide-mega-unbrick-guide-hard-bricked-t3405700
There are a lot of guides that tell you to do this and that, but most of it is not necessary. For example, you don't need to install root access. But if you want the Google Play Store, download an OpenGapps package from opengapps.org, choose ARM64 and the right Android version (7.1). nano or pico should be enough, in doubt choose nano. Install that zip file right after you installed the ROM, with no reboots in between.
I use Linux for adb and fastboot. For Debian/Ubuntu it is as simple to install as typing "sudo apt install android-tools-adb android-tools-fastboot". On Arch, IIRC "pacman -S android-tools". Not sure about Windows.
degen Also how are you setting to to 65/255 brightness?That brightness manager seems to be gone.
Wow, it seems it's really gone. That is most unfortunate, but some other simple apps should be able to do that, too. I just don't know of any right now. Look for screenshots that show values 0-255 and stay away from any "dimming" apps that change the colors.
Or search for "brightness manager igor Tseglevskiy" and download it from some other, trustworthy app store.
Almost forgot: if you choose to stay on OgygenOS, the brightness is 68.