If you see a red hand symbol on your watch, it means the watch is too hot. To protect itself, it will shut down until it cools off. Unplug it from the charger and move it to a cool, shaded spot. It should return to normal on its own.
Your watch may have overheated because:
It was left in the sun for too long
A charging cable or plug was used that doesn't work with the watch
The watch was dropped or got wet
If you get continuous overheating, check out your replacement options.