I came across a customer whose phones were all dead. Nothing on the screen. Ksu has power, flashing blue and red light. I take the phone with cord and plug directly to the ESI 1-4 or ESI 5-8. At least that should work, nothing worked. I reset it many times. held down the red reset button for 10 seconds, nothing. I opened it to make sure nothing was loose, all secure. Also tried the analog port, nothing. What could it be? I have yet to have a bad system (1100 or 2100). Not sure if it is just a bad card or KSU is totally bad. I did not try a laptop with PcPro.