If your firmware is a more recent version (V3 often indicates updated hardware), clicking the link on the login screen might pull up a QR code.
Does your device screen show a when you click "Forgot Password"? 7004t-lm-v3 password reset
If no reset jumper is visible, removing the internal battery can sometimes clear the system clock and trigger a reset on older firmware: How to Reset DVR Password If your firmware is a more recent version