RT-AC66U - 2 dead LAN ports, USB ports extremely hot

Yesterday I woke up to find that I had lost my Ethernet connection to my AC66U on LAN 1 overnight. Up to now, I was only using LAN 1 and LAN 4 (LAN 2 and 3 were empty). I tried a different cable in LAN 1, no difference. I tried LAN 2, and discovered it was also dead. LAN 3 worked. LAN 4, which had also been in use before this happened, continued to be OK. So, LAN 1 and 2 are now dead, 3 and 4 work.

Also, while fiddling around with the cables, I noticed that the 2 USB ports between the power...

RT-AC66U - 2 dead LAN ports, USB ports extremely hot