hardreset problem for A33


hey guys

I tried to hardreset my tablet by usual method power + volume (+) but didnt work that´s why i wonder if there´s any way to get it done.

Besides, another option might be done by using its original ROM which i dont have right now

i leave some info below this post
Model T7 quad (claro)
Allwinner A33 Quad core:confused:
main:M86_MB_V1.2http://es.logicmobility.com/t7-specs/

thanks in advance