If a classroom iMac will not start, try the following:

Depress the button on the rear of the device.

If the iMac does not start, hold it for about 15 seconds (you may hear a response from the Supredrvie if it connects) and then release the button.

Press the button again to initiate sign in.

Mac mini's are typically setup with a local account (username based on classroom or conference room location: i.e. 200dyer) and w/no password.  

If presented with a sign-in option, select classroom or conference room with no password.

If presented with Admin prompt, contact the Service Desk at (401) 454-6106.