Hard Reset By hard reset do you mean unplugging the unit and then powering it back up?

DVR16-8600 Hard Factory Reset
Please follow the steps below to reset the DVR.
1. Power off the machine, remove the power plug from the back of the unit.
2. Take off all case cover screws located on the back and side of the DVR and remove the case.
3. There will be a small black button on the motherboard located towards the front panel of the unit, take note of its location.
4. Carefully plug the power back into the unit, leaving the case off.
5. When the unit has fully booted up, press the black button and wait for the DVR to completely reset.
6. Once reset, unplug the power cable, replace the case and screws, and replace the power cable.
The unit should now be reset back to factory default.
https://support.swann.com/dvr16-8600-hard-reset-ryyDThhaaPM
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Try this hard reset method:

• With the unit powered on, press and hold the reset button on back of unit for 30 seconds

• Without releasing the reset button, unplug the unit and hold reset for another 30 seconds

• Plug the unit back in STILL holding the reset button a final 30 seconds

Perform a 30/30/30 reset; aka Hard Reset.

Hard Reset (aka 30/30/30 reset): The following procedure will clear out the NVRAM and set dd-wrt back to default values:

• With the unit powered on, press and hold the reset button on back of unit for 30 seconds
• Without releasing the reset button, unplug the unit and hold reset for another 30 seconds
• Plug the unit back in STILL holding the reset button a final 30 seconds
  

Try hard resetting;

NOTE:
Some TVs have a reset button. If available and accessible, try using the reset buttons before using the steps below. Using the reset buttons can save time.
Figure 1: Example of the reset button labeling on the LC2600N

1. Unplug the TV power cord from the power outlet.
2. Unplug any connected devices (DVD, Set-top boxes, etc...)
3. Press and hold the TV power button for five seconds.
4. Plug the TV power cord back into the power outlet and turn on the TV.
5. Open the on-screen menu to confirm that the TV is responding again.
6. Turn off the TV and reconnect the devices.
7. Turn on the TV.