[Q] Tablet S stuck at boot loop, unrooted device topic

this is my friend's tablet s. Whenever i turn it on, the tablet will be stuck at the boot loop and nothing will happen. I tried to go into recovery and factory reset the whole tablet but it is still not working. So what should i do? or how can I get the official rom to flash back into the tablet? the tablet is sgpt121a1/s. thx