Hello everyone. I 'm afraid I've fried my SD633. I was testing a non- original external DC power supply. After connecting the mixer it worked perfectly for a few minutes, at some point I disconnected the power supply. The unit switched to batteries flawlessly. But when reconnecting the external power supply, It abruptly turned off. after that it doesn't turn on anymore. Not any LED lights up (anyone) and does not respond to power cycles and hard resets. Anyone of you ever suffered a similar problem? it is possible that the equipment has been damaged? or there is a possibility that possess some kind of protection and possibly react after a while? Thanks in advance.