STEP 4: Flashing the LG K40 kdz firmware using LGUP
In LGUP you can see the model number of the connected phone i.e LM-X40MM. This is the model number of LG K40.
The current firmware version is X420m10d. We’re going to upgrade the firmware to X420mm10g.
The next step is to load the kdz firmware file for flashing.
Tap below “File Path” on the “BIN File” bar as shown in the screenshot above.
A “3 dots” icon would appear. Tap on it and browse for the downloaded file.
Locate the extracted kdz file on your computer and select to open it in LGUP.
The kdz file “X420MM10g_00_MPCS_US_OP_0808.kdz” is loaded in LGUP as shown above.
Now change the Process from “REFURBISH” to “UPGRADE” and click “Start” to initiate the flashing process.
Watch the progress in the LGUP window and keep the phone and USB data Cable intact to avoid disconnection between the phone & PC.
At around 80% the phone has rebooted. Wait for the process to complete.
The progress bar now shows 100% and the process is COMPLETE!
We’ve successfully updated the LG K40 firmware using LGUP.
For any query or feedback, please leave a comment below
Good evening!
I have the brand LG K40 plus dual sims this is also possible for this method and this firmware?
No, this firmware is for the LG K40 MetroPCS variant lm-x420mm.
Hello & good morning. ☺
I’m having issues with my lgk40…what exactly would happen if i didn’t receive or finish the latest firmware update? I need to know if “screen going black” or screen issues could occur. Thank you for your time.
Nikki D
It’s not mandatory to update your LG K40 system firmware. Moreover, the latest update is a minor security update. The major update would be Android 10.
I have a LG K40 that was being used on metro by t mobile & the previous owner broke the screen & i replaced it with a new one but, the files had been corrupted so I had to reset it. After the reset, it has X420TM firmware. Do you know if it would it be possible to flash this Metro firmware onto it to make it a metro carrier phone or would i just need to keep the x420tm & sign it up for metro?
A reset cannot change the phone firmware. X420tm is the model number of T-Mobile K40. You cannot flash a MetroPCS firmware on a T-Mobile phone. You should just register it for Metro.
I have a MetroPCS K40 (lm-x420mm), but use t-mobile service. I know the phone will work as-is, but (considering the last question/answer) can it be done in reverse? i.e. can t-mobile k40 firmware be flashed on a metropcs k40 phone?
Not possible
Hi, I’d like to ask- I have an LG K40 by Metro PCS which was bought in the US and brought to Cuba. It was unlocked as far as to work with the Cuban carrier, but the 3g and 4g mobile data connection does not work. I have it understood that this phone works in the 900 MHz 3g frequency and Band 3 LTE which are the frequencies in which the Cuban carrier provides the data service. Could this problem be solved if I flash itwith the original ROMand unlock the restrictions imposed by Metro? Thanks in advance.
ROM Flashing won’t change anything.
Where can i found firmware for a LM-X420AS? if there is any?
What if I try to do this with a lm-x420bmw? It simply does not proceed or remains in a “brick” state?