Have you attempted any troubleshooting steps for this such as resetting the watch through either the Galaxy Wearables application or through the settings menu on the watch itself? Have you noticed any patterns with when the message appears?
If you have attempted the troubleshooting steps and they have not solved your problem I would be happy to assist you further. Please send your full model number and serial number in a private message: http://bit.ly/2JH2rq2
I returned mine to the place of purchase. My son has a Galaxy watch 46mm that he has had almost a year and he has the same issue with it overheating. You should consider returing the product if possible. Samsung has not made any attempt to rectify this issue...and resetting the watch, turning off many features and looking at many websites and this forum does not seem to resolve the issue.
@userOL7Y8vP832 We have followed up with you in private messages. Let's continue the conversation there. :-)
My watch is 2 days old. worked fine 1st day. Today it will stay on maybe 10 mins gets hot and shows the cooling down message and then shuts off. Really disappointed and dissatisfied. Samsung needs a fix and quick.