A slew of problems after a third-part screen repair!

Hi all! I have an iPhone 6 that I have had for just about a year now. A week ago today I dropped it an totally shattered the front screen. Nothing was damaged from a functionality standpoint- it was just annoying to deal with. I was referred to a guy who replaced iPhone parts and I sat and watched him as he took his time to take apart my phone and replace the screen. From the get go, I knew something was off because when he turned my phone back on it flicked on dimly, and then brightened up.. Like there was some lag and my home button stopped working when he finished as well. I took the phone anyway, and as the next twenty four hours went on other weird things started to happen. My battery drains ultra fast and charges very slowly and gets really hot. Sometimes when I unlock my phone it doesn't want to register my swip to unlock it. And if I try to do anything too quickly with the touch assist my phone just locks up and goes dark. Now on top of that I'm stuck searching for service and I'm afraid there's nothing I can do to fix that.. He's already bought a new screen to replace mine now as well as a battery and when it comes in he is going to fix it... But do you think that will actually help? Have I just completely ruined my phone and scrap it and go back to my five?