So I just replaced the LCD panel on my Thinkpad T420, after I slipped on some very icy stairs last week while it was in my backpack and cracked the screen. After installing the new screen, whole columns of green pixels are stuck on. This is a step up from shattered LCD, but it does make things hard to see and (obviously) very badly green tinted. Here's a picture of what it looks like:

screen closeup showing columns of green pixels over various colors

The new screen arrived in good looking condition, except for one slightly bent mounting bracket, and was well packaged, so I don't expect it was damaged in shipping. There were no problems with this before the fall/replace. Here are my hypotheses on what the problem might be:

  • The screen is defective (in which case I need to contact the seller about it soon)
  • I accidentally damaged the LCD cable during the install (it was attached to the old panel with very strong tape and required a moderate amount of force to remove)
  • Something other than the old screen was damaged or knocked loose when I fell

My intuition is leading me to favor the "I damaged the cable" explanation, but I'm really not sure. Does anyone have any idea what the most probable cause is, before I buy a new cable (they're not too pricey but shipping will probably be expensive)?

Edit: So I've ended up getting a new machine. I got a good deal on ebay and it seemed smarter than continuing to pour money into this one. Unfortunately it also means I don't have a definitive answer to this question. If I ever get a chance to find out, I will and I'll update this question again.

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    Well if you still have it apart, disconnect the cables and reconnect just doing a simple reseat of applicable cables, etc. may resolve the problem. If you're able to power on the laptop without putting it all together whiel you move the cables, etc. that may offer some clue if you notice when you mode the cable the colors change or it gets clear, etc. Hopefully you can troubleshoot and power it off and on making adjustment without having to take it all the way apart and put it all back together during your testing... That'd be painful if so but good luck!! – Pillsbury IT Doughboy Feb 18 '17 at 22:27
  • Thanks for the suggestion, but that was the first thing I tried and unfortunately I got no results. I could make other strange things happen on the screen, but nothing I did could make the green lines go away and I didn't see anything to definitely convince me that it was a cable issue (eg columns of red lines appearing). – realityChemist Feb 18 '17 at 22:31
  • FAULTY DEVICE... Contact the seller you purchased this from -- as unlikely it is, this appears to be the case. You got it from the package (don't say you think you were too rough, etc. doesn't matter make them prove that). you received the package, put it together with great care; this is what's going on and nothing more. Please help me trouble shoot why this new LCD I purchased from you is NOT working, or send me a new one.... It's really as simple as that and keep screaming at them... period... done... and onto the next one.... Let me know how it goes, call ASAP, and happy to add an answer. – Pillsbury IT Doughboy Feb 19 '17 at 1:51
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    Can you hook up an external monitor to your laptop and see if the green lines appear on both displays? If this is the case, your GPU most likely was damaged in the fall, meaning a new screen will not fix anything. – MrPublic Feb 23 '17 at 1:30

@Mr Public's recommendation is a good way to tell if there was further damage to the laptop itself. (Connecting an external monitor to the device and comparing the display)

enter image description here

If the external monitor displays similar issues, then there is more extensive damage on the laptop.

If it does not, it's possible you may have damaged the cable.

Although, it doesn't hurt to test this idea by returning the screen you purchased and requesting a new one. (Claim the first one was faulty, can't reject it unless it shows signs of obvious damage)

If it still continues with the second LCD screen, I would assume your intuition was correct towards the cable as they can be a bit flimsy at times.

Let me know if that helps.

  • Thanks, I'm working on it. I've put in a request to the ebay seller to see if they'll do a swap with me. Unfortunately the laptop doesn't have an HDMI port, and I can't find my VGA cable, so I haven't been able to check on the external monitor situation yet. I may have to make a trip to Microcenter to pick one up. – realityChemist Feb 23 '17 at 21:16
  • @realityChemist ThinkPad T420's should have a VGA port on the left side of the device you could plug an external monitor into. I will add a picture into the answer. – Cheesus Crust Feb 23 '17 at 21:18
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    Sorry, mis-remembered the name of that port; corrected it in my previous comment. The point stands, I can't find that cable (I had one at some point, but I've moved several times recently and I can't find it now). – realityChemist Feb 23 '17 at 21:20
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    So, I stopped at Radioshack on the way home today and picked up a new VGA cable. I plugged it in, and I'm happy to report no green lines appeared on my external monitor (good news, that would pretty much mean retirement for this old laptop). I've ordered myself a new LCD cable, which should be here soon. I've also put in a return request for the screen; if the cable doesn't fix it I'll do the return, and if it does I'll cancel it. Either way, I'll add my own answer to this question when it's resolved. – realityChemist Feb 27 '17 at 3:11
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    So because I'm out of the country now and can't do the return on time to get a refund, I've canceled it. I'm going to just have to buy a new screen when I get back and eat the sunk cost. Hopefully all this effort will help someone else in the future. – realityChemist Mar 2 '17 at 18:44

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