X2100 Short-Circuit - Burning Cable [SOLVED]

[RobWilco]

After patiently waiting I received my X2100 from jacky and have absolutely fallen in love with it. Running Windows 11, Mac OS Monterey (THANK YOU jamesfawcett for sharing your EFI online!) and Debian have been easy and stable. A+ cosmetic condition too, the only thing that didn't work was sound - which I later found to be a very bent pin where the audio connector meets the daughterboard. Replacing the daughterboard (if that's the right term, the board with modem and audio jacks) from another working X201 I had laying around solved the problem. Updated BIOS and EC using Linux to August 06 version from XYTech which fixed the battery and ac power switching back and forth while using the 60W barrel charger (SHA256: f3d881b112747b598c5bd6e88c997f698bfeb22be0c5326d7dfc03a5033fc850). I only use default BIOS settings which seem to work splendidly and thermals are fine (if my sensors are to be believed in MacOS and Windows it hovers around 48C with a few lightweight tasks running).

Everything has been fine while using it for the past week and a half or so until yesterday I turned the unit on and noticed that the status LEDs below the LCD were off. I turned the unit back off. Opening the lid and powered back on, the LEDs were back on and things seemed fine for a bit. Closing the display slightly the machine appeared to power off and I smelled burning. I quickly pulled the battery out, and while looking at the back of the chassis I saw that the original display cable (which at this point appears to only be for the thinklight and status LED functions, this one has the 3K display with its own cable) was melted on one side - the section that is visible slightly from the back of the laptop when the lid is shut. I touched it with my finger and was immediately burned, so my first thought was that there is a short circuit somewhere.

My thinking was that perhaps since this was an original cable used, it may have had original wear and exposed trace / copper which may have touched metal near the chassis / display. To test this hypothesis, I disassembled the display and took a picture or two, gently took out the old thinklight / status LED cable and placed the one from my old X201 in its place, carefully checking for any worn cables, exposed metal, ANYTHING that might cause a short along the way. After carefully reassembling things seemed fine, system turned on, boots, LED lights working, and I thought I had the problem solved. Unfortunately later in the day I powered it on again and shortly after power on, no LED lights, smelled burning, and I pulled the battery out. Sure enough, the exact same part of the same cable had started to smoke and was burning hot to the touch.
I have visually inspected inside the chassis as well as inside the frame which houses the LCD looking for any worn wires or anything like bent pins, contact where there shouldn't be, but I can't find any.
Assembly looks very good (thank you jacky!), but I'm running out of ideas for what could be causing what seems like a short. I'm willing to try just about anything, I love this laptop and am eternally grateful that 51nb have made the perfect laptop dream a reality, at this point I'm really really hoping it's just some cable or something else obvious that I'm overlooking - I've gotten to taste perfection, I am not willing to let it go without a fight!
Does anyone out there have enough experience to wager a guess as to any other specific spots to check, or know where else could cause this particular stretch of cable to cook? Thanks in advance. Pictures linked.

https://imgur.com/tz6mDyP
https://imgur.com/txpV2ip
https://imgur.com/43dHr0Z
https://imgur.com/xsAGYaV
https://imgur.com/FpcaC7P
https://imgur.com/JgYMEPK

[L29Ah]

> If you're seeing this message, that means JavaScript has been disabled on your browser, please enable JS to make Imgur work.

[RobWilco]

I spent today patiently troubleshooting and I can say with 99% certainty that the LED indicator board was the culprit.
Very carefully inspecting the traces in the cable which runs from the LED indicator board to the motherboard I could see
that the path was direct to the burned segment of cable. With the battery removed I slowly and carefully adjusted wires and connectors, looking for anything
that might look odd. I risked it and decided to plug the power in and see if moving things around would reproduce the short and cause the LEDs to turn off.
No matter what I moved I couldn't seem to reproduce the problem, so I put the plastic screen trim back in place, and when slowly closing the lid (not all the way),
THE LIGHTS WENT OFF so I immediately unplugged the power. I plugged the power back in and when I put light pressure on the LED indicator board the short-circuit would occur.
Placing some electrical tape over potentially conductive metal and relieving a little bit of pressure by carefully adjusting the LCD cable seems to have completely cured the problem for now,
though I'm still wary to leave this plugged in unattended until I can 100% verify.
Now I am typing my reply on it, and I couldn't be happier. The X201 was my favorite ThinkPad I've ever owned, and the X2100 continues to do the portable utilitarian laptop line proud.
I hope if anyone else runs into this particular problem that this may serve them in their troubleshooting endeavors.

[jamesfawcett]

Hi Rob!

I was linked to this thread, I have an X2100 also (as you know! ) Mine has stopped responding today. No status LED's no power or response.

I'm going to strip it down this weekend and try find the fault. I will check these display ribbons.

Thanks
James