Fuel Management and RF Interference
The fuel sensors in the 777 are ultrasonic and bounce a signal off the top of the fuel to measure the tank capacity. If there was waxing in the tank I am sure it would have given some very strange readings very early on and the management system would have moved the fuel if a problem was seen. I imaging this will have been part of the design.
RF interference on the FADEC is possible but very very unlikely. They are designed to withstand massive RF loads, lightning strikes and have triple fall over. Indepentant systems are making calculations then checking themselves against each other and if they don’t agree they alert. A digital coincidence in the form of a misinterpreted signal is statistically possible but then so is time travel. My guess would be a set of complex and rare and unforeseen circumstances and a software fault. But that’s just a guess. 