Precision 7760 - Unable to update BIOS

If you prefer to update BIOS from BIOS boot menu, follow the instructions below:

Installation
1. Copy this Precision_7X60_1.23.0.exe firmware file to a non-bootable, FAT32 formatted USB drive.
2. Insert the USB drive into any USB port.
3. Power on the system.
4. At the DELL logo screen, press F12 to access the one-time boot menu.
5. Select BIOS Flash Update in the Other Options section.
6. Click the ... button to browse the USB drive to locate the downloaded file.
7. Select the file and click OK.
8. Verify the existing system BIOS information and the BIOS update information.
9. Click Begin Flash Update.
10. Review the Warning message and click Yes to proceed with the update.

The system restarts and displays a Flash Progress bar at the Dell logo screen. The system restarts again when the Flash update is complete.

@Chino de Oro​ Hello Chino. I am trying to do exactly what you describe. But I cannot find the ... button on the screen capture above. I presume that this is not normal. I also have a Precision 7530 and it all works as above with the same USB stick.

@christopher.lowden1​ ,

I skipped the general prerequisites assuming you had it covered.  The laptop is not attaching to any other USB devices, docking station, external screen(s), and suspend BitLocker (if used).  

Exploring the following options:

Use a different USB drive, between 8gb - 32gb, preferably non-SanDisk. 
Use different USB ports on laptop.
Check your logs, specifically BIOS events to see any history of issue.
Test with a different BIOS version to see if firmware will display.
Considering to flash BIOS in Windows environment.
Considering to perform BIOS recovery (BR2) but using the latest firmware and with the OS drive removed.

Hello

I found a workaround by activating the network boot services in the BIOS.

By activating the HTTP boot feature in auto mode