Hello @FaridBMS ,
If your MX firewall is online at the dashboard, it's likely that is got the local password from the dashboard network settings (if it did synchronise config successfully).
Assuming config sync is ok, you can re-define local admin password in menu Network Wide -> General ; then, scroll down to Device configuration section and define a new password in Local credentials. Give it about 3 minutes to sync again and you should be good to login to Local Status Page.
If you're still unable to login, perhaps sync isn't working well. In that case, it's safe to do a factory reset and then login using default credentials. Once MX is back online, synchronisation will take place.
You can read and understand more about Local Status Page login here. And here you have more about redefining the local password.
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