Lenovo t420, Just won't boot

[TheSiege]

I have a lenovo t420 that I had left unplugged and unused for a couple months.
It longer turns on. There is no response whatsoever. I have looked at various repair options online.
I have removed the battery and held in the power button as I plugged in the AC adapter and the power button lights up and goes off.

With the battery removed I have tried pressing the power button 10 time and holding for 30 seconds on the 11th time. (supposedly this clears the capacitors or something) I plug in the AC adapter and the power, hdd, bluetooth, optical drive, and the keyboard lights all light up for a few moments and then it goes dead.

I have then removed the hdd, ram, battery, ac adapter and the bios battery for 24 hours then I put everything back in except the main battery and then apply the AC adapter.

I got it to load the bios from a clock error. Then I updated the system clock. I was able to get to the windows logon screen and then I powered down to screw everything back together. After removing the battery and the AC adapter I can no longer get it to boot.

Nor get into the bios nor recreate the bios clock error by removing the bios battery. I still can recreate the flashing lights from pressing the power button multiple times or holding it in while pressing power, but nothing more than that.

When AC power is applied the battery led doesn't even light up to indicate the battery charging. It did light up when I was able to get to the windows logon screen, but again after removing power I am back to square one.

I am at a loss, I really doubt it is the system board. This laptop is pretty new, and worked fine when I left. I know the ram and HDD are fine I have tested them in other systems. Any ideas guys?
please let me know.

 

[corkyg]

Exercise the warranty.

 

[Trader05]

Exercise the warranty.

exactly, lenovo's thinkpad support is really good.

 

[LOL_Wut_Axel]

It should be under warranty, so just get them to replace it.

 

[WackyDan]

If you get to the login screen again... let the battery charge. That should solve your issue. Your mistake was not letting it charge long enough while you had it booted.

Had same issue on another TP with main battery dead... Acted just like yours. Took another battery with charge and she booted right up. If you have a friend with a compatible TP battery then use theirs to boot and then swap batteries.

If that works, you should really check over that battery... check the cycle count and the current full capacity versus the design capacity and perhaps the battery can be replaced under warranty.

 

[JeffreyLebowski]

If you get to the login screen again... let the battery charge. That should solve your issue. Your mistake was not letting it charge long enough while you had it booted.

Had same issue on another TP with main battery dead... Acted just like yours. Took another battery with charge and she booted right up. If you have a friend with a compatible TP battery then use theirs to boot and then swap batteries.

If that works, you should really check over that battery... check the cycle count and the current full capacity versus the design capacity and perhaps the battery can be replaced under warranty.

Can OP try powering on without the battery?
I've got a stack of TP's on my desk and they all work without the battery installed.

 

[WackyDan]

Can OP try powering on without the battery?
I've got a stack of TP's on my desk and they all work without the battery installed.

Nope. Can't explain it, but once this happens you need another good battery in there for it to boot. It is very freaky and exceptionally hard to reproduce if at all. I've seen it on multiple different ThinkPad models. It isn't that big of a deal as it rarely happens, so it isn't some pervasive thing you ever have to worry about.

Usually if the TP is 4 years+ old I check the CMOS battery first, as that is another culprit.