Cant unlock my mpc ren

hi everyone,
I have just bought an mpc Renaissance from gumtree. it is in near mint condition.
I do not have a disk drive on my computer so the seller changed his details to my details on the akaipro website login so that I can download the software from there.
I logged in and saw that the mpc was registered. I then downloaded the software 1.9.7 for Mac.
I installed the software and plugged in my mpc. I turned the hardware on and the mpc screen lit up blue but was flashing and making a slight click noise, no other buttons or lights work or turn on. . A pop up then came up on my software saying that I had to unlock my mpc and to enter the serial number. I entered the serial number on the back and then double checked the serial number on the product register on Akai Pro website.
when I entered the serial number it just keeps saying serial number invalid? even though it is correct on my hardware and on the akaipro website register?
im not sure what to do... help please. so much money for something just to say invalid..........
cheers.

you need to call Akai on the phone and reset the count of available unlocks (4 in total), plus I would ask them to re-registering the mpc renaissance under your credentials.

if you are in Europe I do recommend to call the German help desk, they do speak English.