Computer froze with garbled screen, blank screen on restart

[random fuzz]

I'm using a T400.

When I was using my laptop it suddenly froze with a garbled screen, which reminded me of a problem with a desktop a few years back that would freeze with a garbled screen after a few minutes of usage due to what I later realized was a dead fan on the graphics card. So I hold the power button and shut the computer off. I then try the power button again, the Caps lock, Num lock, Drive in use, and Power on button flash on for a second, and then it switches to the Power on and Battery status button, and the screen remains blank.

After multiple tries with the same condition the laptop worked and booted up. So, since I'm using Linux on the computer I use lm_sensors to look at the fan, temperatures and they seem normal. After maybe a minute or two the screen garbles again and I'm forced to shut it off. Trying to turn on the laptop again results in the same problem now. I remember looking at the SMART data of the hard drive a little while back and I believe it was the Reallocated_Sector_Ct that was high, but other than that the SMART values were okay. Also, if I put a CD in the CD drive, it makes the usual CD noises so it seems to be reading the CD ok, and I can hear and feel the output of the laptop's fan so I think the fan is functioning correctly.

So I'm wondering if it is possibly that the hard drive failed, since the hard drive light never does anything after the initial flash, or if it is another problem. I would have thought if the hard drive failed at least the BIOS screen would have come up, but I don't know how that works for sure. So I'm looking for suggestions on how to further diagnose the problem, or confirmations, if this information is enough to diagnose by, that it is a specific problem.

[Harryc]

Run diagnostics on the T400 using the Lenovo Toolbox or PC-Doctor. Run them all, but concentrate on graphics.

[random fuzz]

Run diagnostics on the T400 using the Lenovo Toolbox or PC-Doctor. Run them all, but concentrate on graphics.

That's a good idea and all, except other than that one time anomaly where it rebooted I can't get anything but a black screen, which means I can't get to a situation where I could run those programs.

[Harryc]

Try a reset. Remove the battery and press the power button 10 times at 1 second intervals, then press and hold the power button for 30 seconds and then release it. Reinstall the battery then try to power up.

[random fuzz]

Try a reset. Remove the battery and press the power button 10 times at 1 second intervals, then press and hold the power button for 30 seconds and then release it. Reinstall the battery then try to power up.

I've tried the reset you suggested a few times with no change, still just a blank screen on startup.

[Harryc]

Remove all drives, all plug in cards, and all memory. Power the machine on, does it beep?

[random fuzz]

Remove all drives, all plug in cards, and all memory. Power the machine on, does it beep?

I finally had time to disassemble the laptop. After removing the hard drive, dvd drive, and ram I turned it on. It did a beep sequence of 1 beep, 3 beeps, 3 beeps, and a final 1 beep.

[Harryc]

Try reinstalling one memory module at a time. Try different slots. Try powering up in between. Any change in symptoms?

[random fuzz]

Try reinstalling one memory module at a time. Try different slots. Try powering up in between. Any change in symptoms?

Tested one of the DIMM in the main slot, the same problem. Tested the other, and everything's okay, including a scan with Lenovo Toolbox. So it appears one of my DIMM died on me.

It seems I still have warranty, so it's a matter of getting a replacement DIMM. Having never dealt with Lenovo's warranty before, do you know if there is any way through email or their website to request them to ship a replacement DIMM? Or would I have to call them or go to a service provider?

[Harryc]

It should be customer replaceable if it is under warranty. Explain to them it failed their diagnostic and ask to be shipped a new module.