Help my Samsung keeps freezing after 10 seconds of turning starting it up

[AC Question]

I first thought it was the battery cuz it drained rapidly and the phone froze a lot so changed it which made its working hours longer but didn't stop the freezing but then i didn't even use this battery for a month when the phone froze on me and restarted itself and it's was stuck on the Samsung start up logo causing me to remove the battery but when i turned it on this time it showed my home screen and i could swipe the screen butbthan only lasted for like 10 seconds then it froze and it keeps dowthe same thing as i restart it. I tried hard-flashing it using Odin but my computer didn't see the phone when I plugged it in. Please what do i do?Ps it's a Samsung Galaxy N7000