Hello there!
You can restore the factory settings according to the method provided by sohaib.ansar, and then reconfigure.
For the login method, please refer to the following information
User name and password
Default settings:
Administrator (installation and maintenance personnel):
User name: telecomadmin
Password: admintelecom
NOTE:
After logging in to the web page, if you do not perform any operations within five minute, you will be locked out and return back to the login interface. Then, you can unlock the account by entering the login user name and password.
Three times within five minutes the user name and password input error, the system is locked and unlocked automatically after one minute.
Modify the password through the NMS.
Certain carriers may customize accounts and passwords, which are different from the default accounts and passwords listed in the preceding. For details, contact the corresponding carrier.
CAUTION:
Please change the initial password to ensure administrator account security.
Do not provide terminal users with the password of the administrator account. The administrator account is used by the carrier for O&M. If a terminal user uses the administrator account, service parameters may be incorrectly modified and services may be affected.
Common user (terminal user):
User name: root
Password: adminHW
NOTE:
The common user account can be used to query the service status. For ONTs that support Wi-Fi and the USB storage function, the common user account can be used to configure services such as Wi-Fi and home sharing.
After logging in to the web page, if you do not perform any operations within five minute, you will be locked out and return back to the login interface. Then, you can unlock the account by entering the login user name and password.
Three times the user name and password input error, the system is locked and unlocked automatically after one minute.
Modify the password through the Web.
Certain carriers may customize accounts and passwords, which are different from the default accounts and passwords listed in the preceding. For details, contact the corresponding carrier.
CAUTION:
Change the initial password after common users log in to the web page.

If you continue to be unable to log in, contact your device provider.
Thank you!