Dell E7270 Unable to update bios

Is there a recognized, at least 50% charged battery in the system?

@ejn63​ It is 99% and power plug in.

Is the AC adapter correctly recognized by the system?  F2 at powerup to check.

If you're updating under Windows, what version is on the system?

@ejn63 It is recognized​

@ejn63​ latest build of Windows 10

What OS is running, if you're updating under Windows?

@Jerome113 

run CMD with admin privilegs.
Navigate to the folder with the your BIOS EXE file and type this command:

Latitude_E7x70_1.27.3.exe /forceit   and press ENTER

Pls post results

Peter 

@petermuss​ It restarts but doesn't proceed with the upgrade. It doesn't show the Dell logo with the updating screen and instead restarts again, going straight to the login screen. Upon checking in dxdiag, the BIOS version is still 1.6.3. Same in stand alone and F12 flash bios.

@Jerome113 

use this video to unplug the main battery and coin cell battery.
Power drain the laptop by pressing the powerbutton for at least 30 sec. after unplugging the two batteries. 
Reasseble and try to upgrade the bios again.

HTH

Peter

@petermuss​ Done still the same. It will do the restart but won't proceed to upgrade. No Dell logo with upgrading progress.

troubleshooting performed.
-unplug bios battery and battery and press power button for 30 sec.
-After the hard reset. Setup bios time. Enable UEFI/ secure boot. Disabled legacy com.
- Do stand alone bios upgrade with version 1.36, 1.13. (Elevated privileges)  
- Do CMD upgrade with version 1.36(Elevated privileges)  

@petermuss I have performed the bios recovery(ctrl+esc) I used the latest bios to update(BIOS_IMG). It proceed to bios upgrade but failed in 100% but in dxdiag/bios steup I see it's already 1.36. I don't know why it said failed in 100%. Thanks for helping.