samsung tab 3 problem please help

my tab 3 just keeps going on boot up loop. ive disconnected battery from mother board and reset it back in place. now it wont charge and screen just flickers on and off. i think its the battery is shot and wont hold a charge and thats why it wont boot up fully.

ive tried the power button and volume button but it wont complet the download and just goes off and screen flickers, do you think i need an new battery???