I also had the problem where my hl l2380dw would not power on occasionally (same socket).
Sometimes switching socket would work, sometimes not. Maybe it was more about unplugging it for a longer time?
In any case, ran into this issue again, saw this post, pulled out the tray (not sure if this is important or not) unplugged for about 30 seconds (a little longer than I had tried previously), and then while pressing the power button re-plugged it in... it powered on immediately.
Strange.