<<When I try to connect to it using Maestro, I get engine error 335544745
"Your login SYSDBA is same as one of the SQL role name. Ask your database
administrator to set up a valid Firebird login". I can't say whether this
comes due to the file damage or this is the way how embedded server should
behave. I tried to connect to this file also by setting up Firebird Server
and to use gfix/gsec, but also without success.>>

This is not due to file damage. Basically whoever created the database set up
a role as "SYSDBA" a well known trick to stop anybody accessing the database
using the default security database and default user name and password.

<<Have you got any suggestions how to try to access/fix that file? I am not a
Firebird expert, so I may have missed something (but I studied a lot of docs
how to try to fix my problem).>>

Nothing simple and straightforward comes to mind. If you want to acess the
database using Firebird's own tools, then you need to get rid of the SYSDBA
role first... or find out what the database owner username and password
really is.

Paul