Dell T20 bios modding questions

Hello guys.
I needed to mod Dell T20 bios with SLIC.
I did that with Phoenix tool 257 (273 didn’t work), as result I have .hdr file.
The questions are:
1. How to flash extracted and modded hdr file to PC and do not brick it? Is hdr file enough or I need something more?
2. Is there better/safer way to do it?

Bios I mentioned: https://dl.dell.com/FOLDER05796041M/1/PET20A20.exe
Modded hdr: PET20A20
Best regards, Mike