In cas you lost the charger, try to buy one locally.
Reference: A charger that fits a 24V12Ah lead-acid battery, with a pin-type output (note that the interface must be the same).
What positions do I need to store the 2 wheeled unit in? Does it have to be stored flat on 2 wheels or can it be tipped up against the wall (I'm concerned about the battery pack)
After assembly, it can be placed normally. No special treatment is needed. When it is not used for a long time, just pay attention to charging and maintain the battery.