ThinkPad T420 Hard Drive Replacement

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Introduction

If the hard drive in your ThinkPad T420 has failed or you wish to install a larger or faster drive, this guide will show you how to replace the hard drive.

Guide notes

This guide does not cover operating system installation.
- While I make no promise or guarantee that I can help, if I know what you were running on the machine before the drive replacement, I may know where to locate an image of your OS.
If you install an SSD or a thin Advanced Format (AF) drive, a 7mm->9.5mm drive spacer may be required. These are readily available online from sites like eBay if needed.
- If you are installing a hard drive, cut the spacer based on the location of the breather hole. Heat WILL kill a traditional drive.
ANY UNKNOWN HDP PASSWORDS MUST BE REMOVED BEFORE REPLACING THE DRIVE. IT WILL TRANSFER AS IT IS BACKED UP TO THE ATMEL CHIP ON THE BOARD!
If possible, make a backup of your original drive and image it. This is optional, but it can help you recover if something goes wrong.
- Note: This is not recommended for used systems. Reinstall from scratch and make a clean image from a fresh install.
Once you are done with the old drive, if you do not need it, securely erase it.
- Note: The procedure to wipe the old drive will vary by type. SSDs should be erased through a process known as "ATA Secure Erase" when possible to avoid putting wear on the SSD when it can be avoided. The drive will reset the encryption key, rendering the data unreadable.
  - NOTE: For HDDs with SED support, a similar process where you can reset the key can also be used. However, it generally requires the manufacturer tool as it was patched into the firmware (whereas it is natively supported on SSDs).
- IMPORTANT: Legacy non-SED HDDs will still need to be wiped in a tool like DBAN, which takes hours or potentially days for larger drives, even with a 3-pass DoD wipe.

What you need

Step 1 Change note

ThinkPad T420 Hard Drive Replacement, Change note: step 1, image 1 of 2

ThinkPad T420 Hard Drive Replacement, Change note: step 1, image 2 of 2

Tool used on this step:

Essential Electronics Toolkit

$29.95

Buy

Due to the EET missing several components present in the Pro Tech Go and only being $20 cheaper, the EET has been removed. The EET will work for this guide as-is, but if you are shopping for a new toolkit to complete this guide, the Pro Tech Go (new or refurbished, refurbished is ~$32 cheaper), or Pro Tech ($79 new/~$59.95 refurb) is the current recommended toolkit for this guide.
If you are interested in a refurbished kit stock levels change frequently but can be found here.

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Step 2 Unlock the battery

ThinkPad T420 Hard Drive Replacement, Unlock the battery: step 2, image 1 of 3

ThinkPad T420 Hard Drive Replacement, Unlock the battery: step 2, image 2 of 3

ThinkPad T420 Hard Drive Replacement, Unlock the battery: step 2, image 3 of 3

If completing a step like a clone of your old hard drive/SSD, DO NOT remove the battery until the process is complete!
Unlock the latch locking the battery in the laptop.
NOTE: To remove the battery, the tab must be held in to avoid having the lock reinitiate inside the laptop.

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Step 3 Release the battery

ThinkPad T420 Hard Drive Replacement, Release the battery: step 3, image 1 of 3

ThinkPad T420 Hard Drive Replacement, Release the battery: step 3, image 2 of 3

ThinkPad T420 Hard Drive Replacement, Release the battery: step 3, image 3 of 3

After unlocking the battery, remove the battery from the reverse way it is installed to remove it from the laptop.

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Step 4 Backup your laptop first!

ThinkPad T420 Hard Drive Replacement, Backup your laptop first!: step 4, image 1 of 2

ThinkPad T420 Hard Drive Replacement, Backup your laptop first!: step 4, image 2 of 2

If your build of the OS was installed years ago, you can clone the drive as shown here or reinstall from scratch. However, a reinstallation from scratch will likely be the better choice for older installations with excessive file buildup.
Before replacing the drive, backup your personal files. This can be done by hand, or automated.

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Step 5 Remove the hard drive door

ThinkPad T420 Hard Drive Replacement, Remove the hard drive door: step 5, image 1 of 3

ThinkPad T420 Hard Drive Replacement, Remove the hard drive door: step 5, image 2 of 3

ThinkPad T420 Hard Drive Replacement, Remove the hard drive door: step 5, image 3 of 3

EET owners: Your kit has this bit. No purchase needed.
Remove the hard drive door from the system. Use a Phillips #1 bit.
Once the screw is loose, remove the drive cover as shown.

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Step 6 Remove the hard drive caddy

ThinkPad T420 Hard Drive Replacement, Remove the hard drive caddy: step 6, image 1 of 3

ThinkPad T420 Hard Drive Replacement, Remove the hard drive caddy: step 6, image 2 of 3

ThinkPad T420 Hard Drive Replacement, Remove the hard drive caddy: step 6, image 3 of 3

Pull the black tab on the drive caddy to remove the drive.

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Step 7 Remove the drive bumpers

ThinkPad T420 Hard Drive Replacement, Remove the drive bumpers: step 7, image 1 of 3

ThinkPad T420 Hard Drive Replacement, Remove the drive bumpers: step 7, image 2 of 3

ThinkPad T420 Hard Drive Replacement, Remove the drive bumpers: step 7, image 3 of 3

EET owners: Your kit has this bit. No purchase needed.
Remove the hard drive bumpers.
Remove the drive screws using a Phillips #1 screwdriver.

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Step 8 Remove the old hard drive

ThinkPad T420 Hard Drive Replacement, Remove the old hard drive: step 8, image 1 of 2

ThinkPad T420 Hard Drive Replacement, Remove the old hard drive: step 8, image 2 of 2

Remove the old hard drive from the laptop. If you intend to keep it, store it in a antistatic bag if possible.

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Step 9 Install the new hard drive

ThinkPad T420 Hard Drive Replacement, Install the new hard drive: step 9, image 1 of 2

ThinkPad T420 Hard Drive Replacement, Install the new hard drive: step 9, image 2 of 2

Install your new drive using steps 6 through 3. Reinstall or reimage the operating system.

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Step 10 Install the operating system

ThinkPad T420 Hard Drive Replacement, Install the operating system: step 10, image 1 of 1

If you are installing Windows, use an official ISO or purchase OEM installation media without a product key.
In order to save time setting up your system in the future, reinstall Windows from scratch and image the computer once all the drivers and updates are installed.
After reassembling the system and confirming the new drive is recognized, reinstall your operating system.