Holy cow, it should go without saying that you never force a battery to fit. You may have also damaged the driver by flexing it.

If the driver is okay, then you might be able to just remove the protection circuitry from the battery and add a new sleeve to it. Sleeves are super cheap. Or buy new unprotected cells. Whatever is easiest.

Protected cells are not recommended for this light due to the high amp draw. I’m guessing they made the short battery tube for unprotected cells only.