Hi @vampire_puppy
Let it charge for 4-6 hours and then connect the charger and check if it turns on.
If it hasn't been used for a while then the battery may have been depleted beyond recovery and will need to be replaced. Knowing the model number will ensure that the correct battery is used and also maybe find guide/videos etc for how to do this.
Most probably if the battery is failing then the charger can't do both. Supply enough power to charge the battery and also to run the tablet at the same time and no a more powerful charger won't help either. It will only damage the tablet. ;-)