Locked BIOS on Dell M4600

Hi guys,
I'm the new one on this forum and I have a small problem...

I bought Dell Precision M4600 with locked BIOS and I don't know what to do now. I searched for a solution but only I've got is a deadend...
I've tried to extract hdr file and I actually did it but I don't know how to rename this file and how to enter in recovery procedure??? I'd like to mention that holding END button doesn't work (not broken) while I'm plugging AC adapter, so I NEED SOME HELP, PLEASE...

p.s. Move this thread if doesn't belong here.