Unfortunately. there is no physical switch on this laptop. The dv4 series just uses the touchpad to turn on and off as far as I can tell. It operates the WLAN (enables and disables), but that does not affect the light going from red to the desired blue. I also did a system restore to a point BEFORE the light switched to red, but that didn't help either. Thank you so much for replying though. Any other thoughts greatly appreciated.