Some have speculated that researchers consciously flipped the layout so that dialers would slow down, giving the switchboard time to register the numbers.
Programming was done by plugging hundreds of wires into plugboards, sort of like old school telephone switchboards, in order to set up the computer to perform the right operations.
More modern examples include telephone switchboard operators being replaced with automatic switchboards in 1960, and robotic arms replacing human painters in car factories in the 1980s.
The operator, Tepco, has released a picture of a dead rat near one of the switchboards and suggested that that could have been the cause of the power failure.