Dear customer, after several months with a car sit, several problems can be generated, the most difficult to solve is that the key is deprogrammed with the ignition system, which is very frequent.
My recommendation is that you start by checking the status of the fuses and relays because when installing a new battery even installing the current one, the sudden change in voltage can cause some fuses to burn out.
Also, I do not recommend that you use the same battery, even if you get the right voltage, the amperage may not be correct, normally the amperage can be affected when the load cells of a battery are damaged and when they are flattened for so long, they can get stuck.
Then, check the key fon battery which may also be flattened.
And finally, reprogram the key with the key vehicle's recognition system.