I just recevived my Oculus Quest, and I found there is some liquid leaked out from batteries. Hope Oculus would have an eye on the quality of batteries.
Going from the title of the topic title I thought it was going to be the headset battery, luckily it's just the AA batteries for the controller and not the headset battery. Throw them away (or recycle) and buy yourself a good pair of rechargeable AA batteries.