If your car is going to be parked for several days, the most likely thing is that the battery is discharged.
The car battery discharges because there are several circuits that drain a current: alarm, leaks from dirty and wet cables, electricity leaks from the battery itself and other modules that you do not know have been installed at the factory.
First of all check that the battery terminals are clean and firm.
Check that the battery hold-down bars are secure.
Also check the electrolyte level that is not below the lead plates, top up as necessary to cover the exposed lead plates.
Warm up the engine every 2 days to recharge the battery for 10 MINUTES WITH THE BONNET OPEN, thus preventing the engine from overheating.
If the car is going to be stopped for more than 7 or 8 days then disconnect the negative terminal of the battery so that after 1 or weeks you will have a well charged battery.