You will see which version you have when you boot the box on the LCD little screen, it will show you the version of SSL. Or if you go in WebInterface mode to flash images.

The "INVALID IMAGE (OR OLD VERSION)", means you are flashing wrongly the file. The file is not for your box model (Don't mix DM800HDse and DM800HD, these are 2 different boxes) or you flash a full image and not only the SSL84J file as you should when your box has an older SSL than the version 84.