I was able to resurrect my WM100. Turns out it was connected to a bridge router that was getting connectivity over powerline and was somehow disconnected. Once this issue resolved, I was able to bring the WM100 back to its original configuration.
What I cannot answer is why it wouldn't let me bring it online as a new device, i.e., I've got it where I want it, but reinitiating setup or factory reset failed to work.