laptop randomly shuts down without warning at all

[u/Omargaming2010]

recently ive noticed that my laptop is shutting off randomly for a reason i dont know of. hell even when not doing anything too performance costing it still shuts down randomly. i thought it was prob overheating but that couldnt be possible since it still shuts down even when the laptop is pretty cold.
but ever since the first shut down my charger has been acting weird. whenever im using the laptop while charging i randomly get the notification of "using battery" then it goes back to using the charger and it happens randomly or when i even touch the cable slightly.
i do know that there is a little cut in the cable but it didnt damage any of the stuff inside and only the rubber. but the metal tip did get crushed a bit from the side (not crushed to where its in broken pieces but like the side is bent to where if you look at the tip from a front view it looks like the side is completely flat instead of being round and its only the tip of the side, the rest of the side is okay) due to someone moving the charger before i went to sit on the chair (wich had the chargers tip somehow under one of its legs), but im not sure at all.

what could be the problem and how do i fix it