I am posting this in case someone else runs into this. This happened again but this time the 150FD would not come back to life, even after leaving it unplugged overnight. It is working now, here is the scoop:
Searching the web I found someone mentioned the power switch on the left side. I figured unplugging it would have done the same (or better) thing. Not correct. Even after unplugging several times for many hours, it would not work. But pressing the power button to turn it on/off/on did the trick! The screen showed the input selected and I was happy, but not for long....
The 150FD is fed via a DVDO VP50 video processor, when I turned it on the 150FD went blank again! When I unplugged the VP50 HDMI and did the 150 power button trick the video started working. So something the VP50 did trashed the 150FD video from working. So I did a full reset of the VP50, reset the 150FD power button and all is well now.
I have had the 150FD and VP50 paired since 2007 and this has now happened only twice, the first time (above) I did not have to reset the VP50 so did not know it was involved.
Although I have a VP50 I realized that the 150FD could be adversely affected by a bad HDMI signal in such as way as to make you think the Pioneer went bad. I wanted to post this since I found other people that had similar issues. So if you have a Pio go dark (BTW, the plasma lit, you could tell in the dark) it can be recovered. After almost 2 days I was about to give up and replace it with the ZT60 or F8500. I am really glad I didn't give up. Hope this helps someone.