NAS 542 dead

Always thanking Mijzelf, I want to add some info about what happened to me: I've tried to reinstall the firmware in the classic way (manual update), due to problems with not working backup service, and some other little strange behaviours. The problem has occurred again, the same, so that I can say that was not my fault in the first try: the firmware upgrading process stops at 99% and a message appears

and after about 30 minutes I've clicked the link; the NAS has bricked again…

Now I'm trying to rescue it again…