You could try a factory reset via the recessed button on the back of the router (most makes / models have this function) however you will have to reconfigure the router from scratch if you do that - any firewall rules / port forwarding etc. will need to be re-entered, as well as your connection username / password. If that fails, and your router is under warranty, then you should get a replacement.
If PN supplied it, the DCT will be back on the case later this morning and should be able to organise a replacement for you.
ETA - actually, a red wireless light appears to mean you have your wireless security turned off, so that may be a red herring, however if you can't access the router via ethernet either, then the factory reset is probably still your only option.
http://www.plus.net/support/broadband/hardware/technicolor-582n-setup-guide.shtml#troubleshooting
