My iPhone isn't turning on?

Hi everyone, I was hoping if anyone could help me resolve this problem or at least narrow it down. So my dad gave me one of his bosses phones that he uses for work and he said that the phone stopped working, or the battery died or something along those lines. So he bought a cheapy iphone cable to try charge it from the work van and apparently it started smoking (probably an over exaggeration). So he gave it to me and asked me to fix it. I try powering it on, but it still shows the battery logo and tje charging / cable signal. Therefore meaning it's not totally ruined. I ordered a new charging port and installed that. To no avail. I tried installing a new battery (not OEM) but stuck with that one as the original got stuck in the phone so I had to like bend it out. I have no clue why it's not turning on. To add to it, the home button is broken so a hard reset isn't in the question. The phone won't power up at all, or even show the 'needs charging' logo. I know it's not completely broken, but I'm not entirely sure what could be the problem. Please reply ASAP.

Thanks,

Brandon.