Open a web browser (Internet Explorer, Firefox, Chrome etc) and go to
www.dell.com/support/drivers
If you are asked to "Identify your product", then either enter your Service tag, or select "Browse for a product" to select manually.
If the system shown is incorrect, click on "View a different product" and again either enter your Service tag or Browse manually
After the correct system is selected, you may have to click on the tab that says "Find it Myself" then look further down the page, where it says "Refine your results:". In the pull-down Category menu, choose BIOS. This will refine the results to show only the BIOS category.
If there is more than one file listed, Click on "View details" on the most recent version of the BIOS. Then click on "Important Information".
Click Download File to begin the download
Save the file to your Desktop
Once downloaded, you can double click the icon on your desktop.
Follow the on-screen instructions to complete the installation (Figure 6). This will reboot your system and perform a BIOS update
For more support you can use Dell Latitude E6420 Manual- guideusermanual.com/product-name-latitude-e6420-manual&po=344640&lang=English