Last week, my XPS 15 wouldn't power on. When I plugged the power adapter into the port, the LED light on the cable's tip would go out. A bit of Googling led me to find it was either the charging port or the motherboard.
Since the charging port was the cheaper of the two, I started there. No joy. I then ordered a new motherboard from Dell. After replacing it, the laptop now refuses to power on. The LED indicator on the charging cable remains lit when inserted into the laptop.
What's happening now when I press the power button, is the WiFi indicator light lights up. No activity on the screen, no POST, no anything.
I took it apart again and replaced the CMOS battery, checked for any bad connections, looked for loose wires and can't find anything out of place.
I had a replacement motherboard sent because by all accounts, it looked to be dead.
I have now gone through two replacement motherboards with Dell. I suspected it was the power button or something in between the button and the mobo.
I found a replacement palm rest cover that had all the cables attached. When I installed the replacement palm rest with all the new gear, nothing happened when I pressed the power button. I then tried swapping parts from the new cover to the old one, one at a time. I ended up getting the same results as before.......nothing happens except the WiFi indicator lights up. Once again, no activity on the screen, no POST, no beeps, no hard drive spinning, no anything.
Power supply is good. Battery indicates a full charge. I have tried the discharge trick.
I had this issue after replacing my wife's hard drive. The solution was a ribbon cable from the power button to the motherboard wasn't seated properly. Check that cable.