This is probably a complete newbie question, but I've searched and can't find the "correct" answer anywhere (have tried 10+ methods I've found online and none have worked).

I have a 2013 Elantra Limited Sedan. It came with the Hyundai factory remote start key fob. The batteries died so I replaced them with 2 new duracell units. The fob no longer works to lock, unlock, or start the car. The 2nd remote start fob that I have works without issue...so I'm guessing the one that I replaced the batteries in needs to be reset or re-synch'd with the car? Does anyone know the correct method for accomplishing this?

The style of OEM Hyundai remote start/unlock fob I have is pictured below. Thanks for any help!

 

Yesterday I tried swapping the batteries around in all different polarities....same result for all unfortunately. When I do have the batteries in at the correct polarity tho, the little "LED-1" light at the top of the board blinks 10 times...wish I could find what that means - pic of the LED below: