ORA-27102: out of memory (Startup)

You have started up with pfile.
Remove SGA_* parameters from your pfile.
In pfile, Change your MEMORY_MAX_TARGET=500M
MEMORY_TARGET=500M
Save the file.
Perform the following:
SQL> startup nomount pfile='\u01\app\oracle\pfile\pfile.ora';
SQL> alter database mount;
SQL> alter database open;