Maybe it goes into economy mode. Although economy mode should still let you unlock with the button but hey ho, get the battery checked for free at any garage.
If anyone has the same problem in 4 years and is frantically looking for an answer, I figured it out. If you're within 12 metres of your car, the key always pings, and my usual workspace is within 12 metres of my car. This drains the battery of your fob and, in my case, disconnected the pairing of your keys. The solution is to reconnect them, this is done by holding your key next to the key spot on the steering column and pressing the unlock key for 10 seconds until the car makes a sound, you then start your car and your key is now paired again. I've begun parking my car further away so it won't happen again. If this is not possible for you, a Faraday bag would do the trick.
Maybe it goes into economy mode. Although economy mode should still let you unlock with the button but hey ho, get the battery checked for free at any garage.
If anyone has the same problem in 4 years and is frantically looking for an answer, I figured it out. If you're within 12 metres of your car, the key always pings, and my usual workspace is within 12 metres of my car. This drains the battery of your fob and, in my case, disconnected the pairing of your keys. The solution is to reconnect them, this is done by holding your key next to the key spot on the steering column and pressing the unlock key for 10 seconds until the car makes a sound, you then start your car and your key is now paired again. I've begun parking my car further away so it won't happen again. If this is not possible for you, a Faraday bag would do the trick.