BR600 odd shutdown now no compression?

My BR600 has been on light duty homeowner use since I got out of the biz in 2009, its always run perfectly all the way up until today when I shut it down. It was running normally but when I turned it off it kinda pinged/rattled/clattered a bit as it spooled down. No nasty crunching or banging, just a subtle "ting ting ting" as it came to a stop.
Now it wont restart and its lacking most all compression.

I wanted to ask around here before I pull it apart... Is this a known issue?
Your...

BR600 odd shutdown now no compression?