I’m not an EE or even a particularly smart guy. That said, I did see a phone plugged into a charger, stuffed into a seatback start to smoke and within 60 second the entire plane was filled with a strong odor and it was thick enough to be uncomfortable. Fortunately, we were 30 minutes out and had just begun initial approach. The lead FA had the mitts and a bag that contained the offending device.

The battery in a smartphone is minuscule compared to the one OP is talking about. I marveled at how quickly something so small could wreak such havoc in a relatively large plane (753).