The terminal's screen may be blank after connecting to the machine. Pressing Enter will usually bring up a login: request.
If no characters appear upon the screen after pressing Enter do not panic. The machine must have power and the operating system must have booted: for our call to be answered by the modem Data Terminal Ready must be active.
The most likely thing is that the machine booted and is running a fsck filesystem check. These checks can take some considerable time, all with no or very little output.
It will help your peace of mind considerably to record in the system log book the time fsck takes to check each filesystem.
If you see garbled text after pressing Enter then there are mismatched bit rates or parity parameters. Correct your terminal emulator's configuration.