onda v989 allwiner a83t octa core 32gb bootloop beacause i installed chainfire 3d :( i cant fix it, please help
You just need to flash the stock firmware (ROM) for your tablet, this will overwrite all modified system files. 
Since it is powered by Allwinner chip, you need a tool called PHOENIXSUIT (in English) or ONDASUIT (in Chinese) to flash the image file. Click this link to get the flash file (ROM image). Don't forget to unzip first.