front display screen gone!

[sat_rrstm]

All of a sudden my receiver's front display screen went off tonight and a yellow tiny light is flashing slowly at the down right corner of the ethernet socket at th rear pannel.
All other functions of my TM-6900 Super are OK,it works fine,I mean.
What kind of a troubleshot is this?

[Ghostleader]

Is the ethernet port working?

[sat_rrstm]

Never used it,should I test it?

P.S. As soon as I plugged in my router the display screen came back and the yellow led instead of flashing,its goes off instantly in the same speed it was flashing previously!
In the "IP Settings" directory all lines are numbered when I enter,but ater a second they all turn to zero except MAC Address.
Any conclusion?

Update : As soon as I unplugg ethernet cord the screen goes off again!!!