The device needs reboot after the GUI remains into the loading screen as there is no escape command.
GUI remains in loading mode
as handling process I backtracked the exact process that was used until the gui entered the loading screen. Whne i reached the step at which the ip address of the management interface was changed the root cause of this was obvious (as stated in previous filed = Cause Analysis)
When trying to change the ip address of the management interface from the gui the http session will be shutdown as the session was created with the initial ip address.
When configuring a device , especially for the initial configuration, use the CLI(either through ssh or console port).