Linksys WRT4GL Help

I'm trying to help a friend with his Linksys WRT4GL router. He got it
working himself, but then the power was turned off in our neighborhood
for a couple of hours and it won't work now. It's on, it says the
internet is working, and I can connect to it wirelessly or through the
ethernet port, but it neither sends or receives any packets and I can't
access the internet or the browser-based configuration utility.

I'd appreciate it if someone might be able to point me in the right
direction.

Thank you,
Trevor