What RB3011 is this? Is it in a 1RU case with internal power supply with IEC plug or an external DC power supply? Is the external power supply OK? Can you swap it for another?
See if it makes any difference if you try powering up the router with no patch leads connected, give it a couple of minutes to boot then connect the patch leads
Can you give us the output of /system routerboard print?
What is connected to port5?