First, what region are you in? There are two firmware, one for Australia & New Zealand customers and one for everyone else.

* Download/save the correct firmware for your region
* Extract the ZIP file to its own folder
* Open the the folder
* Per the Firmware_Update_Instruction PDF, you should only have the U3415W USB upstream cable and the U3415W mDP to DP cable connecting the U3415W to the computer
* Nothing should be plugged into the U3415W USB downstream ports
* No second monitor should be connected to the computer
* Open the Windows Device Manager and be sure that the U3415W appears under Monitors and that the Universal Serial Bus controllers do not have any bangs
* You then ran the file, "Dell_U3415W_Firmware Updater_M3B103_Window.exe"

Did exactly what you suggested except HDMI instead of mDP/DP (only HDMI in my PC graphic card). With and without (according to instruction all video cables should also be disconnected). Same - zero - result. No monitor detected.

Monitor in Windows is correct.

No other USB connections

Best

P

- Close the updater software
- Turn the U3415W off
- Disconnect the power cable from the U3415W
- Press the U3415W power button for 15 seconds
- Reconnect the power cable to the U3415W
* Turn the U3415W on
- Try the updater again. If still no go, your only recourse is to request a used/refurbished U3415W monitor exchange. The replacement U3415W should have the latest firmware pre-installed on it

Thanks.

I'll try, because this blinking is annoying.

One more question please (it's a bit messed in instruction) - shall I use notebook (and only USB cable) or PC (USB plus HDMI, anything else disconnected).

Best

P.

Thanks - I try, because this blinking is very annoying. 

One more question (it's not clear in the instruction) - shall I use PC and USB/HDMI connection or notebook connected to monitor only by USB?

Best

P.

I would try them both =
U3415W USB 3.0 upstream out port --> U3415W USB 3.0 cable --> Laptop USB in port
Run the firmware installer

Then if no go =
U3415W USB 3.0 upstream out port --> U3415W USB 3.0 cable --> Laptop USB in port
Laptop HDMI out port --> U3415W HDMI to HDMI cable --> U3415W HDMI in port
Run the firmware installer