Firmware uppgrade problem.

Hello. We have problems with two XDC2460. After we tried to upgrade the firmware we cant access the controllers. Dont know what happened, maybe the files where corrupted. I have tried to download new firmware with roborun+, different version of dfuloader on 2 laptops. No contact at all eather with serial or usb. When i try to download with roborun+, it says its connected but its not. It dosent matter if the controller is connected, its the same message. The led indicators shows: power steady green, status flashes red 1 sec, then steady green and usb is off. Is there any way to load a new software???