Welcome here in this hive!
Does not seem to me an BATTERY ONLY issue, its somehow related for sure, but not the main thing.
As hawk writes, its really smtg which has to be sorted out, coz might destroy your starter motor, AND more expensive, your freewheel assy within the engine.
Maybe you start in a different order as I described,
startswitch frist and then all other
-METIN box and fueltank cover out
-on scoots RH sides upper frame you see an device with a RED/Green or BLACK/Gray plastic caps on it and thick cables, this is your start magneto, which might be faulty by corrosion and sticks sometimes
-take it out, benchtest (YT video) clean or renew
(aftermarket pieces do as well)
-NO cure?
-RH side handlebar switch off (very tender)
(green plaque in it ?) clean contact pins, dielectric grease or coppergrease
-dismantle LH switch assy, there is sometimes a groundfailure to find too
-NOT a remedy?
-MULTIMETER at hand or somebody who knows how to use it
-front plastic "TIE" off from scooter
-under your front there are several relays, one of them is your starter relay
-good battery and try to change relays with each other
-measure voltage during starting process...
Pls come back for Qs. or feedback