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Blank Screen on Dell Inspiron 14 5425

Issue:

Got the thing used, upgraded the harddrive, it was working for months. Now the screen doesn't come on anymore. It was literally working fine and then when my girlfriend went to open it up one day, it just wasn't working anymore. And there is no obvious damage. It did not fall. It was not exposed to heat or cold, etc. It was always kept in a padded laptop bag with a snug fit.

Here are some things I've tried:

  1. Hooking up an external monitor... waiting long enough for it to maybe be booted into Windows, tried Win+D, also tried FN+F8, no dice, nothing on any of the external monitors I've tried.
  2. Tried removing the RAM -- this did result in blinky codes on the charging led (amber/white POST codes). Put back in the original RAM, no more blinky codes, upgraded the RAM, no blink codes -- the LED is all solid white as long as there is good RAM is there.
  3. Disconnected the battery (both the main battery + RTC battery), held down the power button for 1 minute. Reconnected and turned back on. It does the power up, power down a few times thing and then just sits there with the keyboard lights on, until I turn it off. Still no video.
  4. Holding down the D key at power up -- nothing shows up on the display panel.
  5. Shining a flashlight at the screen to see if there is a picture but no backlight. (Seems to just be dark. Might be an OLED display? If I understand correctly, this trick doesn't work on burnt out OLED displays?)

Other Observations:

The battery is working great. Able to charge it up. Turn it off/on, and the keyboard lights up.

The RTC battery has over 3v.

I have inspected the mainboard and screen panel PCB under a microscope, I'm not seeing any obvious signs of damage to any of these components...

I've noticed that all of the LCD replacements for this system are either for the 2-in-1 or for the non-touch. I'm not even finding anyone who sells the touch version of this display for a normal Dell Inspiron 14 5425 / NV140WUM-N42 (30-pin, with Touch).

Next steps(?):

I'm thinking about checking the voltages on the screen panel LCD test points, but unless otherwise marked, not sure what to check for...

I could order a new LCD panel but they're expensive and the one I have now might be fine... it might be the LVDS cable, or it might be the motherboard... -- I would like to test the panel somehow with a test kit or one of those HDMI-to-LCD monitor driver boards. But I can't find any that specifically support the 30-pin NV140WUM-N42 panel, or any that have even remotely the correct connector for it. Not sure where to search to find such either.

Questions:

- Any other ideas, folks? Anything obvious that I'm not thinking of?

- Any sure fire way to tell if it's the screen or the main board that is fried?

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Same exact thing happened to me today. the computer seems to be on and I can hear fan noise but nothing will power it back on.

I have tried all of the same steps

Powered off, unplugged battery, pressed the power button 1 min, move RAM from SLOT A to B and RAM from SLOT B to A, unplugged CMOS held the powered button another minute.

Nothing, no LED indications of failure, the device's only indication that it is on is the keyboard backlight and the fan spin.

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@jacieldiaz Dell laptops are fussy about the freaking CMOS battery being above 2.5V >_>. Start there, you will know with a $10 multimeter. Literally every laptop (even HP!!!) just adds boot time and resets the BIOS.

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@jacieldiaz -- looks like in my case it was a bad BIOS update from Windows Update. Since it happend around the same time, you are probably in the same boat. I fixed it with a $13 clip on chip programmer and using the linux flashrom tool. First I backed up the current BIOS, and then flashed a new one from DELL. It's a pain in the ass though.

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@nick Mine is at 3v (and the voltage of a new battery is 3.3v), and it's working fine again after I updated the BIOS.

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Quick update: it looks like the issue was a bad BIOS from Windows Update. I used a $13 CH341A clip on programmer from Amazon to fix it. The file you download from Dell's website is crap though. You have to run a bunch of Python scripts to convert it to the proper format, and some folks are packaging up files that are virused to hell or otherwise malicous (even the Linux ones were not good). So it took a lot of trial and error. Some of the exes that the scripts called I had to compile from source, it was a complete pain in the ass.

If you find yourself in a similar situation, I recommend running every single thing you download through a site like VirusTotal.com, and if it has a single red flag, don't trust it. -- Even if it comes from GitHub.

Also review any source code you run, and/or run it on a VM to be safe. Because... what a pain in the butt. But at the end you should produce a .bin file that you can actually flash to your chip.

If anyone else has the same exact model number of laptop, and is facing this issue, let me know, I can send over the .bin file that I converted.

Also, when you finally do get to the BIOS flashing stage, I recommend using a Linux live install, and the flashrom tool. Not a single one of the GUI based windows ROM flashers that I found were free of viruses. -- And remember to backup the existing BIOS before overwriting it (because your issue might be different, and maybe the old BIOS was fine, etc. This just gives you the ability to return it to that state just in case).

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how can I get the .bin and any possible steps to try this as well?

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A lot of the time when it all checks out, it's the LED array in the panel. I ran into it on two "junk" EliteBooks (one with LD and a good LCD, one with a known good board and a cracked LCD with a dead array) and swapped the LCDs between the units to fix it. That said, my situation was unique in that I was holding a known good panel on a laptop with a motherboard with fatal damage from coffee due to trace damage and part of the PCB being eaten up but it worked well enough to tell quickly.

Since they were already condemned to the junk bin, I didn't lose by trying to build a Frankenstein given the bad board one had missing keys (no, this one DID NOT have the modular keyboard) and a good LCD, so the expensive part was intact. The other one had a bad LCD and intact motherboard, so the part on the bad board unit could save the good board/cracked LCD machine.

You can swap the touch and non-touch Dell LCD assemblies around at will 95% of the time. There are some edge cases where the boards create a potential issue. The VAST MAJORITY of the time, Dell integrates it into the iDP cable and uses the same motherboard on both laptop versions. The exception is the 2-in-1 laptops because of the unique hinge and chassis changes they need :-(. As long as it isn't a convertible, it can usually be interchanged if you drop the touchscreen gimmick. With these Dells, ~$120 buys you a normal NON TOUCH FHD panel. You're welcome, save the money and drop the touch gimmick as it's pointless except on convertibles.

It's expensive due to supply and demand - few people buy the touch model (except on convertibles), so the part cost is sky high. And when you have a convertible, you run into the same cost issue because they aren't as big of a sell as a "normal" laptop.

Here's the link to eBay I used to locate the panel.

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