[Noctis Fusion]

My Samsung Galaxy S5 has been doing this random restarting. So I had just received the Marshmallow update and was in the middle of installing it and it rebooted. It seems some of the update works but the UI is still Lollipop.

Posted via the Android Central App

[Kellogan]

Repeat the check to see if it did update or not bu going to settings, about phone, check for updates. If it did update properly it will say 'your phone is up to date' or no updates available. If not then select the update option to try again.