Ok, the 7604 model does have a hard reset button inside. Steps for hard resetting it are below:
- Disconnect the power from the NVR
- Hold down the reset button
- Reconnect the power while still holding the reset button
- Hold for 20-30 seconds or until there is some kind of signal (NVR will probably beep or the LEDs will flash)
After that NVR should hard reset, if it doesn't then your only option is to go to who you purchased from and ask for a
password reset