I happen to have mine resolved. I tried all the suggestions in the comments above but they didn't seem to work. The phone restarts alright after following the steps but the screen kept loading 'Phone is starting'. It continued for more than 4 hrs. I usually keep my phone on Power Saving Mode so this problem happened in power saving mode after I updated my phone's software.
But I figured a way to access my applications despite my screen not changing.
1. I swipped down to access the notification panel.
2. On the top right of the screen just below your phone's battery icon (or anywhere you see the settings button), click on the Settings button.
3. From this point, go to Applications, click on any of the applications you want to access and click on Open. The application will be launched normally. You can access any part of your phone with these steps. However, the 'Phone is starting' will still be running in the background.
I was comfortable with this solution for a while but I discovered another one which permanently solved the issue.
I swiped down again to access my notification panel and turned off the Power Saving Mode by clicking on the icon. The transition back to battery (normal) mode happened immediately. The 'Phone is starting' was no longer showing. My phone now functions perfectly.
If you do not have the icon on easy access, click on the settings button and navigate to Device maintenance or Device and Battery, click on Battery and enable Power Saving Mode. If your display becomes misaligned, keep switching between Power Saving Mode and Battery (normal) mode
Hope this helps.
