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ThinkPad released in 2011. This version of the T420 is thicker than the T420s and lacks integrated USB 3.0. The T420i uses the same chassis, so most T420 repair guides work interchangeably.

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Power / Startup Issue?

Greetings all,

I have a Lenovo ThinkPad T-420, and it appears to be in good condition. (I found it in my friend's garage and he said I could have it!) But even with a "good" working battery?...or plugged in with a "good" working power adapter it won't power on. its as if there's no power to the device even though there IS a good battery and power supply(and I know the battery and power supply are good because I have ANOTHER T-420 that they came from!) )Its not a bad looking laptop, and I would like to use it, but if its not working I don't know what to do next. Can anyone shed some light on this issue for me? Or is there someplace I ca ship it to be repaired?

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My laptop version is lenovo thinkpad t420.

My laptop is not starting even with/without battery. There is 100% charge when I operate. Suddenly it is power off and not working. May I know the what can be the reason.

Is it problem with batter or charger or laptop or softwares?


Is there not any LED indicators? For instance, my T420s produces a flashing red light. It will also not even make it to a bootloader. I don't think BIOS even starts .




I have a similar issue with a T420. I tried the power reset but it doesn't help. The backup battery has 3.1V.

If I press the Power button, there is a very short flash from the keyboard light but then nothing.

Any Ideas?


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Solution retenue


Try a "power reset" and see if that works.

Remove the charger and the battery from the laptop.

Press and hold the Power button on the laptop for 30 seconds to discharge any residual power from the laptop.

Connect and turn on the charger to the laptop (leave the battery out at this stage) and try to start the laptop.

If it starts OK and there is an OS installed, allow it ot boot all the way to the desktop, let the HDD activity settle down and then shutdown the laptop in the normal manner.

When it has completely shutdown, switch off and disconnect the charger, reinsert the battery, reconnect and switch on the charger and turn on the laptop.

If it starts, allow it to boot all the way to the desktop, allow the HDD activity to settle and then check the charge status of the battery. If it is charging, allow it to fully charge before switching off the charger and disconnecting it from the laptop.

Also check the voltage in the "backup battery" just in case it is faulty and corrupting the BIOS settings

Here's a link to the service manual for your laptop. Scroll to p.38-39 to view how to test the backup battery

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i connect my charger w/out battery to my laptop, no power when i push the power button.


i'm also facing the same issue

my laptop is working in good condition before 10 days I used but when I started a laptop after 10 days the same issue im gatting no power on the laptop I have changed battery, charger & ram but still the same issue. I have followed all steps mentioned above.


@shatrudhan shrivastava ,

What is the model number of the laptop?

Just verifying that there is no indications on the laptop when the charger is connected i.e. no charge light but the laptop has not been turned on


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Hi @Markie T.

The BIOS may have become corrupted, preventing the laptop from turning on.

Try a power refresh to see if this resolves the problem.

Here’s the hardware maintenance manual for the laptop which will help you to do this.

Disconnect the adapter from the laptop, if plugged in.

Remove the main battery from the laptop.

Disconnect the backup battery. Disconnect the battery by the plug and not by pulling on the wires. (see p.83 in the manual)

Press and hold the laptop Power On button for 30 seconds, then release.

Reconnect the backup battery

Reinsert the main battery, reconnect the adapter and try to turn on the laptop.

If it starts there may be a message about resetting the date and time. This is normal.

Note: While you have the backup battery (aka CMOS battery) out, check its’ voltage. If it is <2.6V DC replace it. This battery is a non rechargeable battery and has a life span of about 5 years. Its’ purpose is to maintain the BIOS settings when the laptop is switched off. When its’ voltage gets below a certain point this becomes harder and may result in corrupted BIOS settings which can cause the laptop not to start. Search online for 04W3253 to find suppliers

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Hiya, I have been experiencing the same problem I think. My T420 will not respond to just pressing the power button on. It would only boot up if I plugged the charger in , as if it needed a slight surge of power. I later found out that if I pressed the Esc button and held it down at the instant I pressed the power button, it will then start up as normal, on the battery only. Have tried this several times so far which seems to work for me, unusual though it sounds. Not sure exactly what’s going on but appears to work. Give it a go, and Good Luck.

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Eddie O'Connor sera éternellement reconnaissant.
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