(1) Push the little hole on the chassis, hold for a while, all the settings will be reset to factory default, including IP address, password etc. You need to config chassis again after restore.
(2) If you have another working chassis, put this failed one in the standby bay of the working chassis. Wait for some min, all the settings will be sync.
There are two bays at the right rear of every chassis, one is primary and the other one is backup. The active one is primary. Please see the yellow one called CME.