Try the cable plugged into USB port of a computer. Rock the cable around on the watch. Pull the cable out of watch and rotate the connector and plug it in the other way. Repeat.
I am sorry there is an issue. Other than you mentioned already cleaning the rear connection points, there are a few steps that can be tried:
- With your watch unplugged, hold down the top left power button for 30 seconds.
If your watch did not turn on, charge your watch. Give 15-20 seconds to see if your watch responds and shows charging. If there no response to being charged, proceed to the next step.
- With your watch plugged into the charge, hold down the top left button again for 30 seconds.
If your watch will charge or power on, please try another charging/data cable if possible.
