I droped my new Samsung Galaxy S6 Edge and I thought it was alright until my phone rebooted and stuck in Safe mode. Now I realized that my VolumeDown button is stuck and getting pressed.
Sorry for telling you the truth , but the only way to get out of the Safe Mode of your Device , is replacing the broken button , because while you pressing the Power button , the volume button is being used automatically during the boot , so the phone will boot in Safe Mode , only because of the broken button...
I actually did not figure out what was wrong with my device until I stumbled upon this post. My phone has been dropped, cracking the screen and weakening the volume down button. Apparently it finally gave in and became stuck as well, landing me permanently in Safe Mode. To fix it, I covered the stuck button with olive oil, and used a football air pump to try to force the oil down around it.
After a few minutes of prying at it with my fingernail, it came up enough for me to restart and exit safe mode.
It certainly isn't a permanent fix, but it'll do until I have time to get a new phone!