Router problem

[Pierino]

I just got a used rt-n56u. I cannot connect to it through the lan ports. Wirelessly I can. Port 4 has a green light on even though nothing is plugged in.
I've reset it to factory default twice and loaded the latest fw on it wirelessly.
Any ideas if it is fixable?

 

[RMerlin]

I just got a used rt-n56u. I cannot connect to it through the lan ports. Wirelessly I can. Port 4 has a green light on even though nothing is plugged in.
I've reset it to factory default twice and loaded the latest fw on it wirelessly.
Any ideas if it is fixable?

Check if maybe two of the pins in the socket might be bent and shorting together.

Otherwise looks like a HW defect unfortunately.

 

[Pierino]

No bent pins as I can see. Should I pen it up and look inside?
I opened it up. Nothing obviously wrong.
Should I throw it away? Is anything salvageable?