Were you using a PC with a serial port or was it a serial to USB adapter? If you have a USB to serial adapter, you wouldn't be the first to see the USB driver mangling the output. It's usually a good idea to go in to Device Manager on the PC and make sure the USB port is mapped to COM1, 2, 3, or 4. I don't think that will be your problem, but it needs ruling out IMHO. Try an ethernet cable in each of the 4 LAN ports. You may get lucky and get the required DHCP response. If you do, try telnetting in. If that doesn't work, try SSH. If all else fails (and by all else, I mean rule out a duff serial cable, duff USB adapter, duff driver, duff install of Hyperterminal / Tera Term / PuTTy etc etc) then hard reset it.