The most common cause of a flat battery in a Spaceships campervan is leaving the headlights on.
Even after a successful jump start, the battery may not have enough charge to power systems like the central locking - especially the rear door - because these systems require a stable voltage. The alternator needs time to recharge the battery fully, and until then, some electrical components may remain non-functional.
What to do:
Leave the engine running for at least 60 minutes to allow the battery to recharge
Drive for a longer period — a minimum of 4 hours driving is required to fully recharge a flat battery.
Avoid using non-essential electrical systems (such as the radio, A/C, and fridge) while the battery is recharging
The alternator will recharge the battery while the engine is running, but it takes time. If the engine is turned off too soon, another jump start may be required.