It could be as simple as the LCD went bad. Are you still able to access the controller over network? If so, just the LCD needs to be replaced.
Judging from your description (light comes on but no LCD), I suppose you have the early version of OS 3 which has transparent acrylic case and a microUSB port on the side. You can open up the enclosure, separate the top and bottom layer board, then use a microUSB cable to power the top layer board only. This can decouple issues with the top (processor) layer and bottom (power+solenoid driver) layer.
You can send a support ticket so we can take a look at the issue.