Gen3 not turning on but…

Hello,
we have in the lab a Drobo Gen3 and users told me that it does not turn on anymore…
I have checked power supply that is good. Nevertheless, there is a strange thing: even all cables are removed, the small led on the power button stays burning ?!? Is the a battery inside the Drobo? Can it be “crashed” and if yes a way to try to return to life?
Thank you for your responses.
Best regards.