Dear customer, i observed a problem in the centralized locked system which is in charge of door openings, it is controlled by a module known as the central locking module, this is responsible for controlling doors, hood, rear-view windows (according to the model) etc. There are certain aspects that may be happening in your vehicle, starting with problems of battery not only of the key fob but also of the vehicle, when it has problems in the power supply of the battery the modules do not receive the voltage required for its operation, another important aspect is that the key fob battery no longer has charge which has already been verified so it can be rule out, this happens a lot. These batteries have a short period of time, so they must be replaced frequently to work properly, you should consider the key fob but as it works with the others doors is not likely that the problems is there.
Another aspect to check is that the control has been deconfigured with respect to the central locking module or the same key fob, this may happen momentarily or it may be due to the battery of the fob was discharged and when installing a new battery the control is deconfigured with respect to the central locking module This is common.
It may also be that the same module has defects, or the same key fob remember that it works by signals, when the control does not have the capacity to emit this signal or the module does not have the possibility of receiving this signal.
My recommendation is to start with a computerized diagnosis first, because this can rule out several problems in the electrical system and modules, you can also reprogram the key fob which is usual to get deprogrammed. The diagnosis will also show if the problem is with the module itself or with its wires or connectors that sometimes produce the problem you have.
This works can be done for locksmith and specialist in this system, as well as the dealership.
So, please first proceed to make the diagnostic with the scanner tool, then reprogram the central locking module and the key fob.
If this proccess does not work, then we have to check the module and the key fob to observe if they merit replacement or fix.
Have you understood me dear customer?