I have firmware question for a noob trying to get current firmware from 3.0 ver. and its not working!

OKay so i bought ..well traded a 300$ new drill i got for free for this a  dual fsesc6.6 and it has the sk8 149kv motors but it didnt come with a battery (which i thought was strange) so i got a battery from another board i have 22.2v 8000mah 6s and im not able to get the current firmware to sucessfuly download ...i mean it starts and finishes the download it just says a error message to fast and small to read on the bottom right and then it says i might have to do a bootleg or something firmware so idk ive tried so many things i hope i didnt break anything any tips? thanks!