: The version. Version 15.0 was a massive leap from the older 12.2 code, bringing the aging 3560 into the modern era of networking commands.
You have a bad image or insufficient memory. From ROMmon: c3560ipservicesk9mz1502se11bin download top
It is either corrupt or tampered with.
After reload, you see switch: instead of Switch> . Cause: The boot variable is wrong, or the image is corrupt. Solution in ROMmon: : The version