It is possible the Rx conductor in Cat5 cable has a bad connection.
Try a different Cat5 cable.
There has been at least one instance of brightness/contrast being turned up so high that the characters are illegible.
This would be indicative of an SCP that is malfunctioning, as the characters should still be legible.
Temporary solution :
Step 1 : Connect SCP to XW, CSW inverter or MPPT80 controller without any other devices in the network. Plug network terminators in unused ports.
Step 2 : Press "Exit" button 10 times>Enter>Arrow down 2 times (to get past SYSTEM SETTINGS in SELECT DEVICE menu)>Enter>Enter>Arrow Down 5 times>Enter
You should now see the characters because the brightness has been reduced.
If SCP is under warranty, contact Technical Support for RMA.
If out of warranty, customer may be able to continue to use it if no other abnormal conditions exist.