Hi, I have tried to update BIOS from A09 to A21 on my Dell e5530, but wasn´t succesfull.

I tried run the update from Win10 area (as recommended), the process starts, but once the system reboots it doesn´t start the flashing BIOS. I tried to run update from DOS bootable disc too with the same result. 

I read the tips on Dell forum and tried them all, but with no succes. 

Can anyone help?