You can restore your Huawei P8 back to Lollipop OS from Marshmallow using the official B300 transition firmware package provided by Huawei for Europe. Transition Firmware Details Device: Huawei P8 Model: GRA-UL00 Android: v6.0 Marshmallow > v5.0 Lollipop Build: GRA-UL00C900B300 Status: Official Type: Transition Package Release Date: 8.02.2016 Region: Europe Country: Russia File Name: RollbackMiddlePackage_GRA-UL00C900B300_Android 6.0 to Android 5.1.zip Download Link: Official Mirror | Size: 399.44 MB How to Downgrade This downgrade package is only intended for the European GRA-UL00 variant of Huawei P8. Unzip the transition package on your computer. Transfer the dload folder to the external microSD card. Safely disconnect the USB cable from the PC. Dial *#*#2846579#*#* to open Project Menu. In the menu, go to Software Upgrade > SDCard Upgrade > ‘OK’. Once the device reboots after installing the transition firmware, make sure the Build number says ‘GRA-UL00C900B300’. Now you can install whatever Lollipop build (for the UL00 variant, of course) you want – like B132 using the exact same procedure.