It was powered on, according to the light on the power switch, however there was no video and, the strange part was that we were unable to power it off.
Regardless of how long we held the power button, it just would not switch off.
Most of the folks on the forums seemed to have issues with powering on, not off. Checking the Hardware maintenance manual indicates that this model should have an emergency reset hole, but I believe that to be lies.
We certainly couldn't find it, and had to resort to undoing the screws on the case and using a spudger to carefully pry the case apart.
Exposing the motherboard enabled me to locate the battery and I was able to unplug it for ~10 seconds. Reconnecting it (it just pulls in/out) was enough to sort the problem and the machine (reassembled!) now boots and shuts down okay.
