Thinkpad T410i won't boot (no beep, power LED on, LCD blank) (2518F5U)

Hi,

I have a Thinkpad T410i model 2518F5U. It will not boot.
When hitting the power button, the ring around the power button does illuminate and stay on, but the LCD never turns on. The mic and speaker on/off LEDs come on for a second, as does the Bluetooth LED and the Caps Lock LED, and the LED on top of the display that lights up the keyboard form above also comes on briefly

The fan spins for about 10 seconds and then shuts off. There are no beeps.

I am somewhat experienced with laptop hardware repair/diagnosis. I have already replaced the motherboard and the CPU and still these symptoms persist, which baffles me. I have tried booting with various components detached such as the main battery, motherboard battery, RAM, HDD, CDROM, Wifi card, modem card, keyboard, top cover (trackpad+BT+fingerprint), LCD main cable, LCD second cable (webcam?), speakers, IO subcard (USB,1394,modem jack). But there are so many possible combinations of which components to try removing at once that I am not sure which to try.

I have tried booting with an external VGA monitor attached and nothing shows up on it.
I have not yet done any disassembly of the LCD.

When the laptop was working (with all components as shipped from factory), it was dropped by about 2 feet and afterwards it booted fine but ran very slow (although it was a bit clunky before the drop as well). I added RAM and replaced the HDD (which was failing) with an SSD, and it booted ok for a short time but then started to exhibit the above symptoms when attempting to reboot. A few tries at rebooting would ultimately work but after a few more days it would never boot.

Any ideas?

Thanks

 

If you have not try replacing the hard drive and checking if the monitor works, it sounds like something is short circuiting.

 

Yes as I mentioned I did replace the HDD with an SSD but neither should need to be attached just to boot (to BIOS).
It's hard to check the monitor (LCD panel). Or do you mean trying an external monitor?

 

Not sure if it helps, but you could try the 'secret' powerbutton code: unplug AC and remove battery. Then push the power button 10 times in a row at one second intervals. Next, push and hold the power button for 30 seconds. Then put battery/ac back in and try to boot.

This is supposedly a method to discharge statics (it worked for me once after replacing a display on my X240).

 

Thanks. I tried that originally before replacing any components but I guess I could try it again. But does that secret button code really do anything if the motherboard has been detached from all batteries and power sources before trying to boot anyways?

 

Have you tried another power adapter? I don't know, if the T410i is now seven years old, I wouldn't waste much time on it unless the budget was tight, but that's me.

 

Yes another power adapter did not solve the issue. Well I had already invested so much time in fixing it that I really couldn't give up.
So I decided to do a part-by-part reassembly with the old mobo and old CPU where I booted the machine after attaching each part.
And amazingly, no part (except one) seemed to stop it from booting, and so now it actually fully boots the OS.
But the one part that causes an issue is the battery. If I connect the original battery to the back, the system will not boot.
If I connect another working Thinkpad battery, it seems to boot fine.

So in the end it is really a mystery because I had certainly tried the same configuration of components that ended up working (i.e. without battery) before.
Maybe there is some sort of weak connection somewhere that could crop up again but that I managed to fix by taking it apart so many times.