Dell S4048-ON newbie questions

We had two S4048-ON switches and I would like to upgrade the BIOS and reset to factory.

Is there a step-by-step instructions on how to do it with a usb flash drive?

I downloaded the file ONIE-FTOS-SK-9.14.1.14.bin and was not sure if this is the right one to use.

I also tried:

DellEMC>  enable

DellEMC#

DellEMC# restore factory-defaults stack-unit all clear-all

Answer “yes”

One of the switch apparently entered BMP mode. I searched and found out there is a "stop bmp" command but not sure how to apply it. Do i hit A to abort the BMP loop then enter "stop bmp"?

How to flash BIOS from the serial usb console? 

I basically want it to be configure-less switch without advanced settings.  (I want two QSFP cables to be bridged and connect to another switch, while all the SFP port connect to my computers.)