How instal Leaked BB 10 OS
What You'll Need
Your BlackBerry 10 device
Autoloader for the OS you are installing
A Windows PC (the autoloader won't run in a virtual machine)
How to Install
First off, make sure you do a full backup of your device using BlackBerry Link. If you want to restore your device after installing the link you'll need a backup file and also, should something go wrong you'll be able to restore without having to start from scratch.
After backing up, run the autoloader file for the OS you are installing. You'll see a screen that looks something like this:
Connect your device to your PC via microUSB. Once the device is recognized the autoloader will do its thing. Your device will reboot and the LED will change from red to green. Don't touch it!
Let the autoloader work its magic. You'll be able to see the progress of the autoloader while it's running.
When it's done installing, the autoloader will quit automatically and your device will reboot once more. If everything worked as it should you're phone will be up as new and running with the new OS.
From here you can either set up the device from scratch or restore using the backup file you created earlier. Note that with some OS leaks you may not be able to restore from an earlier backup.
Keep in mind as well that you'll want to do your research before loading up a leaked OS. Some are not full OS versions and may require extra files to fully install and work properly.
Don't assume anything when using an autoloader and always fully read any disclaimers along with the OS version you're installing. Leaks are installed at your own risk so don't hold us (or anyone else) responsible should anything go wrong during this process.
If something does go wrong, you can always reload your current OS and try again.