Whats goin on with this laptop?

Well, awhile ago my cousins dog chewed my laptop wire. the charger, Well they sent me a new one. Ever since then. My laptop had been laggy playin games and stuff. Like it gets real bad like 1 fps like every 15mins lasting like 5 mins, If I unplug it, it isnt so bad. But it still happens. It says my sound cards not plugged in either lol. Sometimes when I plug in the charger it says plugged in not plugged in, on and off for like 30mins then charges fine. Also, my fan sounded like it was messin up the inside like it was grinding against something really really bad. And sometimes the lights like the power on and where the wi-fi light thing, turns off. Like all the lights turn off. But only happened twice outta no where. Whaa is goinn onnnn