3ds_hw_test is a .firm application that tests a 3DS console's RAM for errors. There are plans to expand the test so it checks more types of hardware, but so far these plans are entirely a work-in-progress.
The test will take roughly 30 minutes on the Original 3DS, 3DS XL and 2DS, and roughly 45 minutes on the New 3DS, New 3DS XL and New 2DS XL.
The latest release of 3ds_hw_test (the 3ds_hw_test.firm file)
Section I - Hardware Test
Power off your console
Insert your SD card into your computer
Copy 3ds_hw_test.firm to the root of your SD card
Rename boot.firm to luma.firm
Rename 3ds_hw_test.firm to boot.firm
Reinsert the SD card into your console
Power on the console without pressing any other buttons
Press any button to start the test
When the test finishes, press any button to power off your console and insert your SD into your computer
Open the newly generated sd:/HWTEST.LOG file in a text editor, then scroll to the end and look at the line that says [ARM11] Done. ___ total errors detected.
If the number on this line is 0, your console's RAM is not the issue
If the number on this line is not 0, your console's RAM is dying and you need to either repair or replace the motherboard
Delete boot.firm and rename luma.firm to boot.firm
Power off your console
Insert your SD card into your computer
Copy 3ds_hw_test.firm to the root of your SD card
Reinsert the SD card into your console
Power on the console while holding HOME to enter the fastboot3DS menu
Select [+]Boot from file... -> sdmc: -> 3ds_hw_test.firm
Press any button to start the test
When the test finishes, press any button to power off your console and insert your SD into your computer
Open the newly generated sd:/HWTEST.LOG file in a text editor, then scroll to the end and look at the line that says [ARM11] Done. ___ total errors detected.
If the number on this line is 0, your console's RAM is not the issue
If the number on this line is not 0, your console's RAM is dying and you need to either repair or replace the motherboard
If you do not have a flashcart compatible with ntrboot, choose a different option.
Ensure you already have a flashcart with ntrboot flashed. If you haven't flashed your flashcart with ntrboot yet, refer to this page
Power off your console
Insert your SD card into your computer
Copy 3ds_hw_test.firm to the root of your SD card
Rename boot.firm to luma.firm
Rename 3ds_hw_test.firm to boot.firm
Reinsert the SD card into your console
Insert the flashcart flashed with ntrboot into your console
Note, 2DS users will not need a magnet, as their device cannot physically fold. Instead, move the sleep switch to the right
Press and hold START+SELECT+X, then briefly press and hold the power button for 2 to 3 seconds
Your console should now be booted into 3ds_hw_test
If it did not boot and instead booted into the HOME Menu or turned off immediately, power off your console and try again. You may need a few attempts to get the magnet positioning correct
Press any button to start the test
When the test finishes, press any button to power off your console and insert your SD into your computer
Open the newly generated sd:/HWTEST.LOG file in a text editor, then scroll to the end and look at the line that says [ARM11] Done. ___ total errors detected.
If the number on this line is 0, your console's RAM is not the issue
If the number on this line is not 0, your console's RAM is dying and you need to either repair or replace the motherboard
Delete boot.firm and rename luma.firm to boot.firm
This section only applies to consoles with GodMode9 installed into FIRM0/1.
Power off your console
Insert your SD card into your computer
Copy 3ds_hw_test.firm to the sd:/gm9/payloads folder of your SD card
Reinsert the SD card into your console
Power on the console while holding R+← to enter the GodMode9 bootloader menu
Select Select payload... -> 3ds_hw_test.firm
Press any button to start the test
When the test finishes, press any button to power off your console and insert your SD into your computer
Open the newly generated sd:/HWTEST.LOG file in a text editor, then scroll to the end and look at the line that says [ARM11] Done. ___ total errors detected.
If the number on this line is 0, your console's RAM is not the issue
If the number on this line is not 0, your console's RAM is dying and you need to either repair or replace the motherboard.
Power off the console and insert your SD card into your computer
Copy 3ds_hw_test.firm to sd:/luma/payloads
Reinsert the SD card into your console
Power on the console while holding START to open Luma3DS chainloader
If you still don't see it follow the boot9strap tab above instead
Select 3ds_hw_test
Press any button to start the test
When the test finishes, press any button to power off your console and insert your SD into your computer
Open the newly generated sd:/HWTEST.LOG file in a text editor, then scroll to the end and look at the line that says [ARM11] Done. ___ total errors detected.
If the number on this line is 0, your console's RAM is not the issue
If the number on this line is not 0, your console's RAM is dying and you need to either repair or replace the motherboard