Had this issue a couple months back took it to the Infiniti dealership and they replaced the whole fob and reprogrammed it.... I must advise you though if your car is out of warranty it’s expensive I had mine replaced about a month befor warranty expired and paid zero

 

It turned out that both of my keys had low batteries...I guess they run down due to age more than use. new battery in place and all works as intended.

thanks...

 

Batteries are cheap and usually the issue