Refer to the information at the URL below, and try the settings and operations there.
Clock software update procedure and notes
https://support.casio.com/wat/app/3516/en/
If the software update is unsuccessful even after you set up and operate the watch software as described by the information at the above URL, do the following and then try updating again.
● Between 2:00 a.m. and 7:00 a.m., continually leave the watch in the state described below.
・Stationary (Place the watch in a stable location.)
・Current time displayed.
・Timer stopped.
・Battery fully charged.