My phone is turning off by itself, randomly

Hey guys i got htc desire 830(not 820, 830!) and its really hard to find answers about my phone, like its a fake version but its not, btw, after 1 year of using, its turning off by itself, all same applications as before, also tried some methods like disabling all 3rd party applications, and i did hard reset, still happens, i think its something about hardware, battery or cpu, if anybody can help me, pls do it ;D im raging when my phone turns off in the middle of youtube video… thank you for reading