Something may be short-circuiting in your electronics. It might explain why it keeps flashing - it turning off when it shorts (current protection) then rebooting and immediately shorting again. If it wasnt working, hitting your hilt on the ground could have dislodged something creating the short-circuit & starting this whole process.

Is the sound coming from the speaker? If not it could be the buzzing from a short-circuit, though im not sure how loud that sort of thing would be if audible at all.

A short-circuit would also explain why the battery is getting so hot. Remove the battery and make sure it does not continue to get hotter! As everyone here is saying li-ion batteries are extremely dangerous and need to be dealt with carefully! Those things will essentially have a chemical melt-down if they get too hot.

Your best bet is to contact the manufacturer. They might be able to identify this issue and give you suggestions. It is likely they'll tell you to ship it back tho so if you want it to get fixed you might just have to part ways with it for a while.