I had similar problems and I’m still waiting for my 442 to get back from support... it actually would turn off when I would pick it up and tap the unit on the left bottom. I only had my 442 for two weeks when I had to send it back.. one thing to try is to plug in the ac adapter and power the 442 on and then unplug it to see if it would stay on... normally it would but it didn't for me, also see if the time/ date has reset I think my problem was that there was a loose battery connection and that if I moved if the 442 would loose the connection and turn off and then it would be hard for me to turn it back on. Also when I got it on I noticed that the battery would say it was half charged and a minute or two it would go to quarter charge. Read my post on my experience with support "RMA TIME"
http://www.neurosaudio.com/community/forum/topic.asp?TOPIC_ID=6881