My phone all of a sudden turned off and isn't turning back on

So, I was just doing my own business with my phone, it was charging and everything is fine until without any warning it just turned itself off and isn't turning back on.

I tried to do the reset, the hard reset, and tried to get it to recovery mode but none of it work and I'm not sure what I did wrong, there was only one time when I came back from the tech appointment when I plugged the phone in it shows the battery sign, but after it charged the screen was lit but still in black screen so I tried hard reset again and it just went back to dark, I don't know what I did wrong.

Was it the battery or something wrong with my phone?