Alexey is right! You simply inflate the price. Try to search for analogs of your tablet on such bulletin boards as Avito, Yula, From Ruk to Ruki and find your way around the price.
If nobody wants to buy a tablet, there are several reasons for this:
You are setting too high a price, try to look for the same model on different sites where they sell Used.
This is fake and it is noticeable
No. You can search in your city for points where the equipment is being repaired and try to sell it there, if it does not work out, then you can be told the place where this model will be needed (usually for spare parts).
Also sometimes in communication stores there are promotions, "Bring the old, get a discount on the new", there is such a promotion in the Allo store (Ukraine). But if you are from another country, then for sure there are the same promotions.