Sorry you're having this atypical experience. I understand how frustrating this must be. I will say, I was part of UI8 beta as well and have never experienced any of the issues you describe.
Have you tried booting into recovery mode and clearing device cache? This corrects the vast majority of issues after updating.
If clearing the cache doesn't fix it, you may attempt a factory reset. Use Smart Switch to create a backup prior to reset to prevent data loss.
If the issue persists after a reset, there may have been an error during update installation. You can attempt a clean install via Smart Switch.
If even a clean firmware install doesn't fix it, there may be some kind of hardware issue that happened to coincide with the update. In this case, you will likely need to visit a certified Samsung repair center to fully diagnose the issue and have any required repairs completed by a certified technician.
