Nexus 7 0% charge with new battery

My nexus 7 (newer versiom) is old enough that the battery was dying, I had to charge too often, so I ordered a battery online, and replaced it
I put it on the charger for the night, and today morning it was showing of still charging it.
I switched it on, and I am using it since morning, but the battery indicator has been showing 0% the whole time.
Actually I have to hold the ON button for a bit long to switch it on, and I afraid the tablet has no idea how much the battery is charged, so it is not just inconvenient, but I afraid of overcharging it easily

But what could be causing this?

Thanks