Hello, Deepinder!
The password may have expired. After the password expires, change the OS time on the OMU portal.
Log in to the OMU portal as user admin and choose Local Configuration > Server Configuration.
Change the time to the time when the device starts to be used, for example, 2021-02-18.
Use tools such as MobaXterm to create SSH and log in as the OS admin user.
Run the su - root command to log in as user root.
Run the chage -I -1 admin command. (The first is a capital I and the second is the number 1)
Run the chage -l admin command (the middle letter is a lowercase l). The verification result is shown in the following figure.
Log in to the OMU portal as user admin and change the system time to the correct one.
Please try the solution above.