Replacement screen has stopped working

Good morning

I recently replaced a cracked screen on an Iphone 5, I've done a couple in the past and it seemingly all went ok with no issues for about 5 days until I got a phone call saying the display had gone black. I thought it could of been a fault with the new display but I changed it back to the old one and it doesn't seem to work either. A couple of other thing seem to happened to phone the display stopped working too:

- The phone doesn't seem to vibrating when i switch it to mute

- The volume cannot be turned up or down

- Siri responds with "there is something wrong and i cant answer your questions at the moment, please try again in a bit"

- The digitizer seems to work, as I can swipe to answer calls

Looking at the phone I couldn't see any tears in the cables or any other damage so I'm really at a loss as what could be wrong with it. Any help as to where to begin would be great. Thanks.