Screen stopped working after charging assembly replacement

There may have been the possibility of you damaging the display while attempting the second repair or at leas the display connector. Take it apart and make sure the display is connected. If a computer is at least detecting it, I would imagine the phone is at least booted up to the lock screen. I would plug it into a computer to make sure it’s detected and then attempt to call it, assuming you left it on ring or at least put it on vibrate. But even then if the phone rings on the other line rather than sending it straight to voicemail, it can confirm the phone is at least powered on, booted up, and it just needs a new screen.