Swollen Battery - PB-T5 Power Bank 20000 mAh

I haven’t used my Aukey 20000 mAH Power Bank (PB-T5) in about a year and when I took it out to use it last week it was swollen in the middle and the case was cracked around the edge and I could see inside the power bank. I have sent an email to Aukey support but no reply. This item is a few years old so obviously not under warranty, but how do I dispose of this damaged battery? Any suggestions?