Hi! I will try to assist you:
1. Make sure the battery is charged enough for the tablet to power on or (if it is not) if you can charge it. An easy way to do thisa is to plug in a charger and see if it indicates that it charges.
If it does not charge, then:
a) The battery is faulty or
b) Something is wrong with the adaptor or the "charge-circuit"
In order for a) and second part of b) to be checked, your tablet needs to be opened!
2. If it charges, then it might be the power button. Try to press it hard enough (try not to break it though) in order to make sure it is not a little bit broken or moved. If still nothing happens then your tablet has to be opened!
3. The screen might be faulty as well.
4. If it is none of the above, then it might be the mainboard. In order to make sure it is not the mainboard, you would need to connect it to an external monitor and see if it works with the external one (I think there is no such option in your case, though)
I assume you wish to experiment-check it by yourself. If you just need a new one, then for instance:
1result for maylong universe