You could try connecting it to another router via any of its interfaces, and hope that the previous owner left CDP on and the interface active. Try doing this with each interface until you come to one where CDP works. Then a show cdp neighbor detail should reveal an IP address.
If it has serial interfaces, you might be lucky and find they have a /30 or /31 mask, in which case your partner router can autoconfigure and so reveal an IP address.
Of course, if it's password protected, you will not be able to do a recovery without the console.
Good luck!
Kevin Dorrell
Luxembourg
