Impossible to programm DK-DEV-3C120N

Hello,

I'm currently working with DK-DEV-3C120N dev board, but since two days, it is impossible to programm it and I don't know why ...

A red diode entitled "ERROR" is lit on the board, the only information I get from the User Manual is that an error occured during last programmation but now, it impoossible to load a new programm on the dev board

maybe someone know how to solve this problem ?

thanks in advance