If you are having trouble connecting you Android device to your Linux PC — or more appropriately Ubuntu — using fastboot, and are at loss to find the cause of it, then we may help you a little bit. A Zenfone 2 user over at XDA, SiriusCybernetik, was facing the same issue and what he found out a solution is a simple trick.
What happens that when you use the easiest of methods in ‘apt-get install’ to install Fastboot on your PC, the latest Fastboot binaries are actually not installed. And that causes issue with Intel device, such as Zenfone 2.
If your scenario involves Intel device like Zenfone 2, Ubuntu OS and Fastboot installation using ‘apt-get’ then you could benefit from this solution.
What you need to do to fix the Fastboot drivers is download the latest Fastboot binary version 1.0.32 and replace it with the old fastboot binary apt-get method installed on your Linux PC.
Download the Fastboot version 1.0.32 from here. And then replace it with old fastboot file currently installed on your PC. That’s it. This should fix the ‘device not recognized’ issue on your Ubuntu PC and Intel powered Zenfone 2.