Ive trying to unlock an old T610 without much sucess. All the SEMC software kept saying was:

“Connect to phone
ERROR: Phone not power up”

Love the use of English there. Well it turns out that you require a T28 Service Cable (or others), NOT a T28 Data Cable. I did not know there where two different cables. So all you have to do is mod the data cable to change it to a Service Cable. This can be done fairly simply, just look at this link.
Then the software works a dream, apart from I had to try it a few times to get it working.