Small Fiats use small batteries. The 500 and its Abarth versions have a compact battery under the bonnet with limited reserve, which is fine in mild weather and less forgiving in a Dubai summer with the AC on from the first second. Versions with Start&Stop have a sensor on the negative terminal and need an EFB or AGM battery. The sensor has its own plug, which should be released first so the clamp is not forced off.
No coding is needed after a battery change on a Fiat, though the car may want a few hours locked and at rest before Start&Stop returns. A memory saver holds the radio and clock settings. Vans are different in layout: on the Ducato the battery is under a cover in the cab floor, in the front footwell, not in the engine bay. That takes longer to reach and the battery is heavy, so tell us it is a Ducato when you message.