won't turn on even after new battery

My phone stopping holding a charge, and after replacing the battery with a oem battery it worked fine for a week, then went back to same problem. Will not power up. Sometimes when I would restart it, it would go to a blue screen.

I bought this phone in a different country. Now I am in USA. Could anyone offer help for what this problem is please?

Is it dead?

Is the reason caused by voltage difference?

Thanks