Phone died, unable to charge or turn it on, what can I do?

I had this phone for 3 years and it worked well, but towards the end the battery wasn't charging like before. One day the phone just stopped responding and shut off for good. I thought the battery might've just died, so I tried to charge it but no luck, just says 0% on the charging screen when the phone is turned off. I ordered another battery from Amazon and installed it. Same problem, won't charge at all even if I use a new charging cable. Nothing looks like it's internally damaged, but I haven't checked under a micro scope or taken the phone apart other than a battery replacement. I would like to get this phone working again so I can sell my new one. Is there an easy and simple fix for this ? Thanks for any info or helpful advice.