Android Q Developer Preview 2 is now rolling out to both the OnePlus 7 and OnePlus 7 Pro, the company has announced via its official forums. This build is supposed to be less buggy than the first one, but it's still not completely stable, of course. If you're using your OnePlus 7 devices a daily driver, it may be best to wait.
OnePlus also notes that some features do not work in this build, including Reading mode and Display mode, while the verification window can't pop up in WiFi anonymous connection. The company does not that there is also a low probability of stability issues, which suggests that the build is fairly stable.
If you're interested in installing Android Q Developer Preview 2 on your OnePlus 7 device, we'll tell you how you can do that, but please do note that there is always a chance that you'll brick your phone, especially if you don't know exactly what you're doing. It's also wise to backup your data before proceeding, not only because there's a chance you'll brick the device, but also because you'll need to format your data after Android Q Developer Preview 2 installs.
That being said, before proceeding, make sure that your battery level is above 30-percent, and that you have a minimum of 3GB of available storage space. So, if you're moving from a stable version of OxygenOS to the Android Q Developer Preview 2, this is what you need to do.
First, make sure to download the correct software build, you can grab it here for the OnePlus 7, and here for the OnePlus 7 Pro. Once you do that, you'll need to copy the file from your Downloads folder to the main storage section of your device, you can do that via the "File Manager" application that comes pre-installed on both the OnePlus 7 and OnePlus 7 Pro.
At that point, you'll need to navigate to Settings, then hit System, and then System Updates. Once you're in that menu, hit the icon in the top-right corner, choose "Local upgrade", and choose the right installation package, that you previously copied.
Wait for the installation is complete, and then restart your device. The phone will boot into recovery, and once you're there, you'll need to format user data. The device will reboot after you're done.
That is more or less it. Do note that you'll need a different file if you're moving from Android Q Developer Preview 1 to Developer Preview 2, and in that case, you will not lose any data. If you need to roll back to Android 9 Pie, after trying Android Q Developer Preview 2, you can download the needed files for that by clicking here (for the OnePlus 7) and here (for the OnePlus 7 Pro). Do note that you'll lose all your data if you roll back, of course.
You will find more info about all this over at OnePlus' Forums, and the link for that is included in the first paragraph, just in case you get stuck, or something of the sort.