After my trials and tribulations reported in this thread and this thread I think I may have found the cause of the problem and it's not pretty! This article suggests there is a new breed of malware that, if I'm reading it right, can infect the bootloader itself! I don't think I've got one of the three mentioned there specifically (though I might have) but I think I've got something similar Just to reiterate my specs, if they're relevant, I have an iNew L4 running Android 5.1 on Giff Gaff (which always detects as O2 for some reason) in the UK. it's not a phone supported by CyanogenMod... well... anything really, so compiling CyanogenMod or Android Open Source Project (AOSP), or Ubuntu Touch or something like that is by no means a certainty! The Manufacturers unhelpfully do not have a pubicly downloadable rom either. So can I somehow flash fastboot (I'm expecting it'll be a scary dd command to a usb port...)? If I compile CyanogenMod or something will it compile fastboot for the device or just for the desktop? Is it even possible?