From what I can tell there was a power failure at Neasden control tower which killed the radio over the entire line (explaining the two different reasons given for the shut down). as I type this at 23:45 the line still isn't working between Finchley Road and Stratford. Ie the busy tunnel section. Not good when this happened somewhere before 6pm.
I myself managed to get caught up in all this when coming from Beckton to Stratford this evening. The DLR staff where on the ball announcing it quickly on the trains. So I had a trek to Poplar tonight and then had to fight to get onto a DLR to Stratford which was packed the whole way. Lets only hope tomorrow goes better for the line!