You don't need the power button to restart your Android. If yours is broken or you simply want options, here are two.

Turning your phone's connection off and then back on is the quickest and easiest way to try and fix your signal woes. If you're moving around from one location to another, toggling Airplane mode ...

Tap and hold an open space on the home screen and go to Home settings > Suggestions. Enable Suggestions on Home Screen, then remove at least one static icon from the bottom row on your Home Screen.