A wire unit to one of the formatters is not correctly connected to the Signal backplane (reference 1, 2, 3 for green on image "Formatter connections").

Check the connections between the formatters and the Signal backplane on the Signal backplane side.

A wire unit on one of the formatters is not correctly connected (reference 4, 5, 6 for red on image "Formatter connections")

Check the connections between the formatters and the Signal backplane on the formatter side.