The 'dopen' message you're receiving is not normal and usually indicates an error, though I'd expect to see a bit more information. Since nothing else is showing up on the command line, and there's nothing in the ASE errorlog ... have you looked for any other details in the Windows event logs?
In the meantime I'm wondering if your environment variables are not (being) set properly before you execute the RUNserver file.
Can you try:
====================
cd G:\sybase\SID
SYBASE.bat
cd ASE*/install
RUN_SID.bat
====================
If this works (ie, manually loading the environment via SYBASE.bat) then you should see a message about the 'sa' password being reset (see Bret's example output).