Battery was running low. If he could have lasted another 3 minutes or so he would have survived.
I've actually played this game with my brother before (with a small drone, no explosives lol). It is actually surprisingly fun.
They use lower voltage batteries so it shows "battery low" even when fully charged. After all, why use more expensive batteries when you plan to blow them up
Practically all of the videos I've seen show a low bat warning. I assume they go by a separate timer based on experience and don't actually measure anything on the drone. That would have to be calibrated and is probably too much effort for a single use device.
I actually fly these things as a hobby 😅 it's telemetry data sent directly from the drone. The reason they are always low battery is probably because they fly them pretty far out to avoid getting detected and killed.
Once the battery hits 3.2V or so, you can really start feeling it in how the drone flies. It just doesn't have the power draw remaining for much else. Usually you land at that point to avoid destroying the battery, but in this case... You can fly it down to 2.8ish and still be in the air, but it won't like it and the battery will be damaged.
They are flying in "angle" mode? I can't make even a half decent turn in angle mode. Somehow I suspect it isn't because lacking skill. Maybee spotty connectivity makes drone in angle mode more reliable?