If you are having problems with you Asus ZenWatch , try referring to the troubleshooting page here.
Background and Identification
The ASUS ZenWatch is the first smart watch developed by ASUS released in September 2014. Its distinctive case measures 51 x 40 mm and has bright 1.63" AMOLED screen. One of the first smartwatches on the market to run the new Android Wear OS. The ZenWatch features many innovative technologies such as heart rate sensor, internal microphone/speaker, and 4GB of internal memory. Expected battery life is around 48 hours of mixed use.
Although the newer Zen 2 has since been released; the capabilities, the low retail price, and ease of repair still make this an excellent choice of purchase.
Direct link to ZenWatch Manual