hi jazure, as far as i know the psu lights are the same on lots of models including the mini, and that the psu light should be a solid green from the info here:
if you can check the psu are you using this psu?
“Drobo” AC Adapter Model: EA1071C
another test you could try would be to power all down, and to unplug all power and connection cables from the drobo,
and to then remove all your drives (remembering the order) and to plug in the power and to try powering up while empty… what happens now?
(please only put your drives back into where there were Only when power is OFF though)
can i also check if this was working before?
i only ask because if you got this 2nd hand off ebay or something, then maybe the seller might have included a different psu which might not be what is required for the mini?