How to reset blinking status LED on Xserver (Early 2009)

At work we have received a couple dozen of these Apple Xservers. The HDDs have been wiped on all but one so there's no OS installed. The ID/Status LED on the front/rear panel of these servers (all of them!) is doing the intermittent-blink thing that, as far as I can tell, means "There's an error." This is not the continuous flashing that's enabled by the front panel button to ID the server from the other side. I suspect it's a chassis intrusion indication but that's just a theory The LED begins blinking as soon as power is applied; even before the power button is pressed & while the white Power LED is off. I have tried resetting the NVRAM/PRAM through the keyboard Option/Command/P/R and also through the front panel, using the button next to the status LED to select a function. No help there. I've seen this question and that's the right LED, but that question is about the Server ID usage of the LED, and my question is about the Error Indicator usage of the same LED. I can boot 10.7 from an external HDD but I do not have an OSX/Server disk available and booting OSX Server 10.6.8 to the login screen (I don't know the password) does not clear the indication. How do I make this LED stop flashing?