Laptop goes to sleep mode after plugging in charger

Hello.

I have a ASUS X550C laptop. The original charger broke, so i bought a charger for it at my local market (the brand is "Innergie"), which also works for ASUS laptops. Now since i got this charger, i was experiencing issues where my laptop would randomly go to sleep mode, however, i resolved this issue by turning computer on, removing the charger, and plugging it back in. That seemed to fix it. However, recently, this method stopped working. My computer runs completely fine when it is unplugged, however, when i plug it in, i get a "Low battery" warning (even though i HAD 72% battery), and the laptop immediately goes to sleep mode. Trying to turn it on is useless. It will only turn on if the charger isn't plugged.

Any advice?

PS: I have already changed all my power & sleep options. Everything is set to "Never".

Update: Battery was at 34%, plugged charger in, went to sleep mode as usual. When i turned it on, battery was all of a sudden on 5%, and when i plugged the charger in it jumped to 100%. Then it gave a critical battery warning and went to sleep mode again, but this time it would only turn on when the charger was plugged in.