I have a dvr and I'm trying to access it's operating system to add a script on it. 
  
  
I found that the dvr is using linux based os, telnet is disabled. I tried to enable it by http:///cgi-bin/configManager.cgi?action=setConfig&Telnet.Enable=true and other solutions I found online but nothing worked. 
  
  
Is there a way I can access the dvr via SATA cable or some input on the board? 
  
  
  
https://community.swann.com/dvrs-21/how-can-i-access-dvr-operating-system-4428