Sounds silly but normally bike batteries come out of the box and are acided in the shop then they require a good charge, you might have gotten lucky and the charge the happens from the initial chemical reaction may have dissipated and now the battery is technically flat although it will read a charge on a multi meter of about 11 volts.
Try putting it on a charger for a bit, if you don't have one go get one of the Warehouse ones at about 2.5 amp output they are ideal for slow charging bike batteries.
I suspect most modern bikes should have reverse polarity protection on all the important bits and may even have low voltage cutouts on some circuity.
An as above there could be a main fusible link on the main feed from the battery to the rest of the bike.
Its not the destination that is important its the journey.
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