Chosen Solution
The attached photos, ( if you can see them) show the destructive power stored in an iPhone 6 battery with approx 70% charge on it. After removing it from the phone, I was straightening it back out, when suddenly it started to flare up ! I had to throw it, it bounced off a door and onto the floor where it continued to burn intensely like a signal flare for what seamed like a 10 seconds or so. This would have destroyed the phone had it gone off while removing it, or seriously burnt my hand for sure in a split second ! Set off the smoke detector, filled the shop with soot and fumes, smelt like a welding shop after, just want to say be very careful with these, I have probably swapped out 100 or more batteries over the last 4 years and never had one go off , now I have a metal can full of water right beside me when doing any iPhone battery swap.
Over stressing the battery in the removal process often leads to a failed battery (one of the reasons glued batteries is such a bad idea). Most of the time it just takes a small puncture to set things off. You’re lucky! It could have been worse!
Did you use metal prying tools or any sharp tools to remove the battery? This should never be done. It’s better to use plastic playing cards / flexible cards and some ethanol / isopropyl alcohol instead. Also don’t bend the batteries or pry at them too much it’ll puncture the battery.
