How do I factory reset (possibly bricked) FortiRecorder?

[pariemala]

My FortiRecorder 100D (firmware v6.4.2) is likely bricked; however, I would like to ensure I've exhausted all possible ways to factory reset it.

I have physical access to the device, and at one time or another successfully connected to the console port using a serial cable.

Ports 1, and 2 have SSH, and telnet enabled, and I used to be able to connect to it using both protocols.

I am unable to connect to it using serial, SSH nor telnet.

When the device boots there are no sounds. The HDD led does not blink.

I have been running version firmware v6.4.2 for 4 months without any issues. I use FortiCentral v6.4.0 b69 x64 too. Sometime last week I tried to connect to the web ui and couldn't connect; I couldn't ping anything nor connect using serial. I pulled the power cord, and after reboot it was working as expected. 24 hours later same situation happened. Repeat 2-3 more times, and now it's completely dead in the water.

I would like to delete all videos before sending it back to Fortinet. Do I have any options available?

[dbu]

I believe you are talking about an RMA device. The only thing you can do is destroy remove the HDD if the policy allows you to remove when returning. 
But you do not know what is faulty in your device, it can be power unit issue, may be the HDD itself and you will not need to worry about :)