How to Stop the Application in Infinite Loop

I have already done this to install the 7.44 firmware on my FXT003, but this time (for the 7.46) I get an error message.
After the manipulations described above and with the right cable:
This message with a progress bar.
Installing the downloader in the Wireless CPU’s memory…

And 10 seconds later:

Fatal timeout error: the target is no longer responding

My FXT003 does not respond to any AT command.

Any idea?