What could be wrong with my Lenovo? Please offer some advice?

So I have a Lenovo Yoga 2 Pro. I've had it for about 2 years, and it has been causing me issues left and right. At first it was working great for a solid 6 months, but now it's at it's worst - there's something wrong with the laptop overall.
Basically, whenever I press the power button, the screen won't turn on, BUT the light on the power button is still on. When I first discovered it wasn't working, I tried charging it, with no luck. I tried pressing the force reset button on the side, no luck. If I press the windows button on the screen it still vibrates, but nothing comes up. I can't even hear the laptop running - no fan or anything. Also, when I press caps lock, the light doesn't come on.
I've tried to let the laptop's battery "die" for a few days now by not putting in the charger, but the power button's light is STILL on.
I'm taking it to Best Buy tomorrow to see if they can fix it, but does anybody know what can be the issue? Also, how much would it cost? (running low on money…)

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