My vibrator isnt working

So i just got my vibrator TODAY and I used it earlier and it worked perfectly fine, the batteries are brand new the girl at the shop opened them infront of me and on the box it said its waterproof so I decided to take it in the shower with me, it wasn't even fully submerhed under the water and it stopped working. I took it out of the shower and dried it off, the inside where the batteries go wasnt wet & now it only turns on if I hold down the knob and if i let go it immediately stops.