At 2 am a closet light came on that is controlled by a motion sensor.  No one was in there, so I figured the battery must be low and simply closed the door.

This morning I tried to connect my ISY to my ELK M1 for the first time (second house doing this), and the ISY only has the Power light on.

I rebooted it and the PLM, and it appears to check in normally and after the boot sequence back to power light only,  IP scanner doesn't see it, network switch indicates a 10/100 device is connected, no activity and no address assigned or being requested.

I did power off and re-insert the SD card, no idea why, I just did.  No change.

I have put in a support ticket and if anyone has Ideas in the interim, thank you for your help. 

I got bored, did a factory reset, it took about 30 minutes and it appeared in the IP scanner.  I had to reboot my mac to get the ISY launcher to find it (cached data?), but the ISY came back up. I reloaded my latest back up only losing one new program, which is my fault for not backing up after I added it.