IC chip replacement caused these problems?

Hey Guys, so i had my IC chip replaced, and when the phone came back it is now very buggy. when i go to settings and try to choose wifi it freezes . To the point that i have to reboot. I'm getting

Call failed errors while trying to dial out.

1 in 20 calls that i make go thru.

signal goes from 4 bars to 0 in the same spot that my wife iPhone 6 plus phone stays at full bars.

when rebooting phone it stays at the white apple screen for almost 3 minutes.

tried to upgrade Firmware but i get the same problems.

What do you think is happening or happened?