Tried starting in the morning after power drained, plugged in, everything came back for a few seconds then the screen went black. Can't restart. If I hold powe button down 10 sec machine emits an intermittent beep which continues until I push power button again. Any ideas on how to fix?
It sounds like your system is stuck in the completely empty battery mode (warning tone).
Try holding the cmd+r after you pushed the power button.
To completely reset it, remove power and disconnect the battery, then reinstall.