This video shows you how to flash the blackbox firmware to your OpenLog device using the Arduino interface.
Before you proceed, wait! You may already have the correct firmware! Put a blank, FAT-formatted SD card into the OpenLog. Power the OpenLog with 5v. Wait ten seconds. Power it down. Then remove the card. A file named CONFIG should be on the card. If the file contains only the "baud" parameter, you are good to go.
Some OpenLog devices purchased from Amazon or eBay or Banggood do not work with the Arduino software. If you cannot get the board to flash, you may have this problem. The simplest thing to do if you are in the United States is to order an OpenLog device from MultirotorMania.com. Their devices so far have always shipped with the correct firmware already installed.