Detailed video on how to replace the battery in Wireless Key fob:
Energizer CR2032 Battery on Amazon: https://amzn.to/2DwIU99
Duracell: https://amzn.to/2OBc1sU

Instructions are very simple.
1. Pull the tab
2. Pull out the key
3. Use Key to pry open the FOB
4. Pull on the Battery with a fingernail (CAUTION, hold the unit tight, as the main logic board will pop out if you don't hold the body with the outside cover and you'll have to put the buttons back together)
5. Replace battery
6. Put back together