After some research per your Hardware info:
Your player is built with Anyka AK chip, not RockChip RK chip.
My method is good for RK chip to my best knowledge and I don't have a AK to test.
May be this is why my unhacking method is not applied to your AK chip player.
More unhappy detail see below regarding the AK chip:
Big problems with hacked 16gbs Onda clone (?). Cant low level format or flashing it!!
I guess there is no good solution so far.
Well if your player is still working fine. Just hold on and wait for new unhacking method pop up in the future.
Keep your all media files under 3.5GB to protect your player from becoming brick.
If you would like take the risk, try to repartition or reformat the player in disk management tool under Xp window.
Make sure you have all system file backup first before proceed.