I zoomed in and watched it several times. Looks like the vent with flames starts directly out the back of the laptop, front being towards the chair. That’s were most battery packs are located. Then when the first small explosion happens (0:08) it shifts the laptop’s left side more towards the chair. It looks like the explosion came from a battery under the laptops left side, A 18650 rocket. Blows hot debris everywhere. I don’t see the power supply, but I do see the charging cord coming out of the left side of the laptop and looks like it runs underneath the desk somewhere.
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I have heard people say “set it and forget it” when charging li-ion’s. Please don’t do that. Electronic devices do fail and are sometimes not made of quality parts. Every had a $1000 or more TV fail after a year or two of use. Now your relying on a $20 or less charger to not fail. :person_facepalming:
Never leave a li-ion charging unattended. 