C600 will only boot with external monitor

I have a Lat C600 this one has the short video cable coming from the LCD that plugs into what looks like a extension connector.

The problem, if I connect laptop to external monitor (with laptop lcd display opened or closed or even disconnected) the laptop boots up fine.

With no external monitor, three lock leds light for about one second and go out at the same time the power led light comes on.  About a second late, the back light of the lcd flickers and goes out.  About 5 seconds later hdd led comes on then the computer shuts down.  I had a working display for a C610, plug that display in and I got the same results.  It acts like a lid display switch is stuck, but I don't see one on this model.

Looking for any help, this one has me perplexed.