D-link Router Burned? D-Link Routersection not connectable

[Hagebyhemdata 0]

My friend has an D-Link DI-604 - Router.Yesterday he told me that his router isnt connectable.He ran a couple of tests on his own, but still no connection.Without knowing what were the problem, he got in touchwith a geek guy, that tested his router and found outthat the routers WAN port was burned, and he couldn't use his router more than a simply switch without firewall.So here's my question; how could a routers WAN port be"burned" and still be possible to use the router as a switch?What went wrong with the router when there were Lightning and overvoltage protection attached?