I had a similar prob, i was in terminal and out of habbit, i typed halt in the prompt.... bad idea!
didnt use the Z for the day, and went to use it the next night, and it was dead... wouldnt powerup, no charge light nothing....
so i removed the battery, pressed reset... still nothing, so out of desparation.... discovered that it had powered up and drained the battery ...
to get it back up.... i just had to leave it charged for a couple of hours, before it was able to boot again.... seems it needs a minimum amount of charge at all times..
later discovered a prob, it just wouldn't suspend! everything i tried pressed the off button, it would intantly power up again... that's what drained the battery... the prob was the suspend-resume.ipk... it wouldnt let it go to sleep... removed that and all is good again...