I moved the img file to the platform-tools directory, then typed in the command line...
fastboot flash boot boot.img
this is the error - cannot load 'boot.img' : no such file or directory
I can't find a solution on the internet
I cannot communicate with my device in Windows 8.1 using the command line parameter "fast boot".
There is a yellow triangle with an exclamation mark next to it in the device manager but I have installed universal ADB drivers (UniversalAdbDriverSetup) and Sony's Xperia Companion 2.5 (newer versions need Windows 10). I've rebooted several times and the phone has the blue light on so seems to be connected properly.
I don't know what else to do. Any suggestions?