Fortigate 200 A - No response Management Port or web interface after power cycling

In an attempt to recover a 'locked up' a Fortigate 200 A we power cycled.  In it's 'locked up' state all the port LEDs were permanently illuminated (not flashing to show data traffic [which was present] as one might expect). The screen was showing FORTINET.

We then power cycled the Fortigate 200 A.  It now sits permanently with a blank / black screen but with backlit LEDs illuminated, none of the port lights illuminate and it does not respond to both the Web and Management (cli) interface.  The Fortigate 200 A unit is both obsolete and out of support, but is included in a system we would like to keep going.  Suggestions?