When you depressed the RESET button, for how long did you hold it? IIRC, it must be held for 30 secs to do a full reset to default settings. Check the manual for specifics..
EDIT: Here's the hard reset procedure from the DIR-615 Rev C manual:
"To reset the router, locate the reset button (hole) on the rear panel of the unit. With the router powered on, use a paperclip to hold the button down for 10 seconds. Release the button and the router will go through its reboot process. Wait about 30 seconds to access the router. The default IP address is 192.168.0.1. When logging in, the username is admin and leave the password box empty."