The ONA13HO501/ONA13HO502/ONA13HO503/ONA13HO505 mice has a dongle that is stored under the mouse cover this is needed to connect the mouse as it isn't Bluetooth. Also make sure that batteries are good. Check the manual below for further connection information.
Onn. Wireless Mouse ONA13HO501 User Manual
File: User-Manual-1884304.pdf
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