ZyWALL 5, access password

All of a sudden, I can't login into my ZyWALL 5. I used to connect to it from several computers and now I can't open it from any of them. I enter password (let say it's 5555) and I'm going to endless loop via "Enter Password and click Login." dialog... I tried to use CLI interface (menu item: 23) and set next password to 5556. But it did not help. I returned it back to 5555 and it did not help too :( Now what? How to access it at this point? Is there any other way to set password there? Is security becomes a new nuisance instead of a useful feature?