We are using MK60DN512VLQ10. When we do assembly process in our customized boards for the IC, for the first time if we download the code if it gets downloaded then any number of times we can erase or download the code. But for the first time problem comes in downloading it says that kinetis device is locked, target download has been failed. Then if we try for any number of times we can't download the code to our boards. Again we have to remove the IC from our board and replace with new one. Its a big process to remove the IC and solder with new one. Boards may be get damaged. Now we are in a production stage so we want the ICs in bulk quantity. Can you please resolve the issue. Tell us exactly where the problem comes from.