I was reading this thread and was perplexed, but I think Giz hit it on the head. When plugged, mine beeps, the display pops up, then goes blank. Then if you hit the on button, you get the default setting with can be adjusted up or down.
Otherwise, I couldn't think why the machine would work, then blank. If the fuse blew, you wouldn't expect it to power up the next time it was plugged in.