How to downgrade Huawei P8 B399 Android 6.0 to Android 5.0.1

How to downgrade from Android 6.0 Marshmallow firmware to Android 5.0.1 Lollipop
1. make backup of all your personal data and charge a battery in your phone to 100% (optional)
2. download this transition package for Huawei P8.




3. rename the downloaded file to update (extension .app is important there, don't change it)
4. create folder dload in root of your internal storage and place the update.app file here
5. turn off your phone and than power it with holding all three buttons together (release them when you see Huawei logo)
6. wait until first part of downgrade will be fine, than you will have transition firmware B300
7. now use tutorial for installation Android 5.0.1 Lollipop for Huawei P8.