All credible reporting I’ve seen is relatively certain that it was a small amount of military grade explosives.
If you have the device in front of you, and are prepping it for your secret operation, that also seems like a much more straightforward solution than trying to manipulate a lithium ion battery in a way that both allows it to work normally for years, but then explode violently enough to kill someone holding it.
All credible reporting I’ve seen is relatively certain that it was a small amount of military grade explosives.
If you have the device in front of you, and are prepping it for your secret operation, that also seems like a much more straightforward solution than trying to manipulate a lithium ion battery in a way that both allows it to work normally for years, but then explode violently enough to kill someone holding it.