Reset to factory configuration a DVR

Hello all; I come to this forum to ask for your help; I need to reset my dvr to the Factory configuration, because I changed the admin password and then I forgot it, so I can’t access to the functions. The model is VS101 from V-safe.
I have tested the common passwords like, 123456,123, 321 ,0000 etc. And this DVR don’t have any switch to reset the memory. I tried to remove the battery but only the hour goes to 0 but the passwords don’t changed.
Here the pictures of the DVR:
http://imageshack.us/a/img850/5436/27106334.jpg
http://imageshack.us/a/img803/2010/87627153.jpg
http://imageshack.us/a/img255/2334/32330267.jpg
http://imageshack.us/a/img837/3945/32386883.jpg
http://imageshack.us/a/img811/2760/35833170.jpg

Thanks for your help
Regards