Power your unit on (while on your boat – can be done while on the trailer) and make sure it starts up in its normal operating mode and not the Simulator.
Go to the Setup menu tab and use the Restore Defaults menu to reset all of the menus.
Install the SD card that has the software on it in your Humminbird unit. You should get two questions asking if you want to update the software. Use the left-right arrow to answer them.
Your unit should start updating and will flash different colors. Depending on what software your unit had versus what the update contains it could take anywhere from a few seconds to over two minutes to complete the update. Important: do not press any buttons or disconnect/switch off the power to your unit while it is updating!
Once the unit has finished updating it will automatically shut off and turn back on. When this is done, remove the SD card and go back to the Setup menu tab and use the Restore Defaults menu again.