What's the problem with the GM plant explosion? They were doing destructive testing to see exactly what would happen when you do everything possible to intentionally destroy the thing. They succeeded.
According to the GM report, they were doing "extreme testing of an experimental battery", which does not necessarily mean that they were trying to destroy it. My guess is that they were trying to over charge it, or perhaps heat it up to extreme temperatures.
Whatever test they were doing, the GM plant was clearly not prepared for the explosion that they got, otherwise they should have been able to contain it without incident.
So, was GM at fault for not predicting the magnitude of the explosion, or was A123 at fault for not warning GM about the risks? Considering that GM had the testing lab that was going to be doing the destroying, I would tend to believe that it was GM's responsibility to be aware of the risks. It still looks bad for A123, even if that's unfair.