XPS 12 9250 display stays black

Ouch!!! Being that you had it open, did you chech the screen connector? I bought a refurb XPS 12 9250 for $640. Picked it up by the keyboard while open, and since I carried it slightly tilted the screen fell to the wood floor and broke. The refurb did not have accidental damage so I got a used 4K screen off of eBay for $300. So much for my bargain. While installing the new screen, I also worked on the power button, taking it out and putting  one layer of duct tape on the PCB motherboard side of the switch. I cut the tape from a paper pattern. The switch had a tendency to slip under the very small PCB mounted switch. You may want to take your torx screwdriver and reopen your 9250, check screen connections, and before reassembling it, turn it on by the vey small PCB switch. Before the screen broke, I first opened it up to disconnect the battery after the system froze and was unresponsive. That was before two BIOS updates, and newer drivers. Good luck ElAguila. Keep us posted if you get it working again.

All of the screen connectors are tightly connected. I don't know what is going on with the darn thing but this is very frustrating. I was trying to see if a key combination would get me to a bios screen like the key combos on a cell phone can get you to recovery mode. When I held the volume down button and then pressed the power button, the tablet vibrated and I could see the backlighting of the screen come on which it has not been doing. Then the entire screen turned white the red then green then blue. It would do this cycle several times and then back to the black screen.

Not sure if this will help, but.........

http://www.dell.com/support/Article/us/en/6099/SLN284985

I don't really want to open my XPS 12 9250 to see if I can figure where the CMOS pins are, but seems, barring official Dell support, it would seem you have little to lose. Messing around with it  wouldn't be so bad if this 9250 didn't cost so much.

I just remembered the ribbon cable and screen connector when I replaced my screen. It is very short and a bit difficult to connect. When the screen is separated from the back and you open it like a book, there can be tension on the ribbon cable that might pull it out of alignment in the connector. The ribbon needs to be carefully parallel to the connector when inserting it. I'm 66 years old and I needed a magnifying glass, but I think using one would help anyone. The connector has a thin plastic hinged flap. With the flap up, the ribbon can be inserted or removed. Push to flap down to lock the ribbon in place. This is not the same ribbon connector, but it works like the one in our XPS 12 9250's. Here is a 14 second youtube link:

www.youtube.com/watch

I had thought of reseddtting the cmos but i didn't see the pins. They are probably under one of the several heatsinks on this thing. I will try it again today to see if I can find it. I will also double check that ribbon connector. Thanks for the info. I will let you know if something works.

This is the model # and (for the purpose of finding the CMOS pins) a non-informative link.

Mainboard: Dell Inc. Model 0Y5CWX, browser.primatelabs.com/.../8041181

I can't find a motherboard manual anywhere. Perhaps create a request at Dell about finding your CMOS pins.

Have you tried holding or tapping the F2 key to enter setup when you power on your 9250? Maybe hit the blue Fn key and tap F12 to increase the screen brightness.

Troubleshooting Dell LCD laptop screens.

http://www.dell.com/support/article/us/en/19/SLN129589/en##Issue5

I tried using the function key to brighten the screen but the keyboard is not working.Also I can't see that back glow that the screens have when they come on but haven't displayed anything yet. The only time I saw that was when I held the volume down and power keys at the same time. I am stumped at this point and thinking hardware failure.

If you can't get an image either internally or externally, the odds are overwhelming the system board is faulty.

My coworker and I both got new XPS 12 9250s from the Microsoft website.  Supposed to be their signature edition.  He is having a problem with his holding a charge.  It will not hold a charge for more than a few hours even when it is powered down.  So if you put it in your bag in the evening charged and go to work the next day, it will be completely dead.  I had the same problem with mine.  

Today (only a few days old) this machine is doing exactly what ElAguila is describing.  Only difference is that mine will not even buzz when you hold down the button.  I have had it plugged in and the screen laying down on my desk all morning.  The thing is warm so something is happening in there.  But no response on the screen at all.

Don't know what to say about your coworker's PC, other than questioning if he simply closes the tablet onto the keyboard resulting in a sleep state or actually powers completely down before folding the tablet onto the keyboard.  My XPS 12 9250 lasts a bit less than 4hrs. Do you feel a small click in the process of pushing the power button? The outer switch pushes a tiny roun toggle switch on the motherboard. These power buttons on our 9250's should be pressed with the fleshy tip of finger, definitely not with a finger nail. I found that out when I had to repair my power button. The outer switch slipped under the inner switch preventing the preventing the toggle on/off. I had to take the switch off and then made a paper template which I used and added to the small piece of duct tape cut in the exact shape of the underside of the switch where it contacts the motherboard. This extra bit of thickness (I had to pierce several holes in the paper and tape because of alignment pins and the small screws) slightly lifted the switch to center it directly to contact the small round toggle on the motherboard. Possibly your power toggle was and still is in the power on state, unless you can actually feel that small click I mentioned. If the click is there, then your power switch is OK.

Sorry for the misspelling of round and repeating preventing twice.

It would be good to hear back from ElAguila and others to expand or comment on answers they have checked. Like "It was returned to Dell for repair", or "total loss", or hopefully a successful solution,