Thank you for your quick response!

The cable and plug are in normal condition. I managed to turn it on just fine as well. Fans running and lights on. I had a hard time getting the other cables out as well, everything fits really tight. But nothing like this one. Wiggling left and right and a lot more force than I was comfortable with did the trick, so they came out fine.
Can you please describe the manner you normally pull this cable out? The only option I see left, is trying the "right" way with the cable and using more force than previously. 

I don't know if the miner is fully functional, since I can not make it connect to the web. This is related to electricity issues in our apartment though. Running the miner through the only available power socket will blow our apartments fuse (I know from experience with other electronics that it's the apartments fault though, lots issues with several sockets). From other places I can't reach the Ethernet port of our router, due to short cable. But it turned on just fine.