Need to upgrade from Android ver. 4.4.4 to Android ver. 5.0 with unlocked bootloader I have an Xperia Z and recently I unlocked the bootloader. However now I cannot install (upgrade) to the Lollipop Android 5.0 (10.6.A.0.454) from Android 4 (10.5.1.A.0.292) through the Sony website. I always get the message "cannot be installed because I have an unlocked bootloader".

Please advise on a step by step process to lock the bootloader again if possible or advise on how to upgrade to 5 version. 

Please make it for dummies because I am not experienced or a developer whatsoever.
Actually it's possible to relock the bootloader, using Flashtool. The process can be found on this XDA Forum post.


Download Flashtool from www.flashtool.net
Start Flashtool and click on BLU button
You will be asked to connect device in flash mode
Once you connect the device you will get a prompt to "Relock"
Click on it and when prompted disconnect the device