For me it appears to be an issue with the car sometimes entering a deep sleep (battery saving) state. When my charging door doesn't open using the button on the charging handle, I open one of car doors or wake-up the car using my phone and then press the charging handle button again which always then works. So I think its just an indication that sometimes the car is in a deep sleep mode and doesn't sense the signal from the charging handle or maybe is ignoring it because the car is locked and hasn't yet sensed my nearby phone.