Studio has invalid serial number

I just bought a MPC studio off ebay but it has an invalid serial number! whats the best way to go about this?? especially since the seller is not responding at all

What do you mean? It may need to be re-flashed aka updating the firmware. If it was used on a mac then used on a pc or vice verse you will need to re-flash it. I had that happen to me. It wont unlock the software? If it wont unlock the software contact Akai via this link and ask them to reset it http://www.akaipro.com/support hope this helps