Lenovo Laptop Turns on Only with Charger, and then Turns Off

So I have an issue, where first (1), the laptop does not turn on unless plugged in. And second (2) when it is plugged in, and I turn it on, it begins to boot, showing the logo but them turns off. It also sometimes shows 'starting automatic repair' but turns off afterwards anyways. The battery, even when I left it charging for a while, stays at 69% (yes, really) and for context, it spent unplugged and in my backpack for a week, since I was travelling away from home (the backpack was mostly motionless). I've tried to disable inbuilt battery and then draining the board, but it didn't fix the issue, I think. My laptop is an Ideapad 5 (ALC05)