Hi, I have just bought myself a SSD for my Macbook Pro mid 2012 running El Capitan and decided to buy a caddy for my old SSHD to use as an external drive. I plug the external drive in and in disk utility go to the drive to try and format it but I just get the message 'Erase Process Failed'. The SSHD is 500gb with 150 gb as a windows partition, is it possible to format the drive?