T420S is Randomly Shutting Down

[alpuzz]

Hi,
Trying to troubleshoot a frustrating issue with a refurbished T420S that I recently purchased from the Lenovo outlet. I bought the machine for my mom at Christmas, and everything worked great for the first few months. Recently, the machine began exhibiting odd behaviors, popping up messages saying that a USB device on the system was not recognized, even when nothing was connected to any of the external USB ports. The screen then began randomly displaying static and often times when the static would happen, the machine would also unexpectedly shut down. I have already placed one service call, and the technician replaced the keyboard as well as the motherboard. I was pretty confident that we had seen the last of the issue; However, it’s unfortunately still occurring.
The problem is that it’s so random! Yesterday, I did a clean reinstall of Windows, spent several hours playing with the machine, installing updates, etc., and it worked fine. Gave it back to Mom last night. She used it throughout the evening and it worked fine. This morning, it crashed on her again. She is using the same power supply and isn’t connecting any devices to the USB ports. I’ve run most of the Lenovo hardware diagnostics I can find and they all check out.
At this point, I guess I have no choice but to send the machine back to Lenovo; However, I’m very afraid that they’ll get the machine, put it on the bench, and it will work fine. The issue only seems to occur when someone is using the machine. We can leave it on for hours on end, overnight, and it’s still up and running when we come back to it.
What is Lenovo’s policy on refurbished machines if they seem to be lemons? It does have a one year warranty. Do we just need to keep playing the service call game until they get it right, or do I have any other recourses?
Thanks,

[ideal-pc]

Have you tried checking the memory? Sounds silly but I had an old Thinkpad edge a few years back & I would get random bluescreens for different errors & like you sent it back under warranty. They said cooling system was duff so replaced it & the motherboard. Fine for a while & then the same! The errors just got worse & worse to the point it was rebooting every 5 mins or so. Turned out to be a bad memory stick. Not always easy to diagnose though as some memory issues don't show up on some tests. I would get the free memtest bootable cd from Passmarks website & leave it to do a few good cycles & see if anything flags up

[Brad]

Besides the memory to check I would continue to make those calls for service explaining that there have been more than one unsuccessful attempt at repair.

My experience with this type of issue is that possibly the ThinkPad case itself or another part is causing the problem.

When calling for service explain what has been done so far. I would request a bottom base replacement citing the continuing issues.

Brad

[AIX]

You need to have the motherboard replaced in order to have this problem solved. I had my T420s' motherboard replaced two times before the "static display and the unexpected shutdown" gone away. See this thread:

T420S Crashing into TV like fuzzy screen