To run force backup you need to connect to the server using ROOT
login.
Once you have connected to your server, run the following command :
/usr/local/cpanel/bin/backup
You will receive output that backup has started at xx date time along with the location of it’s log file.
cPanel / WHM backup log file location :
/usr/local/cpanel/logs/cpbackup/
Make sure you have enabled backups prior to running this command (WHM >> Backup Configuration)