[Elecraft] Kat firmware download fails

[eckhart.neumann at icloud.com]

Hello
In the process of updating my KAT500 it lost the firmware. I can not reload it. Error message is:
firmware block write failed at address 2304.
A forced download as described in the manual failed with the same error message.
I use the utility with a Mac.
Any help would be very much appreciated. 
73, Eckhart, DK2LJ

Eckhart Neumann