Hi and thanks in advance for your help.

I'm new to phone firmware's - I have a Galaxy S7 I bought off ebay and Wi-Fi Calling won't work because the firmware is not UK O2. I read about how to update with Odin and then bought another S7 off ebay for my Mum as she needs a new phone . I tested updating the firmware on the new phone and all went through fine (and put my Sim in it and wi-fi calling is there!). I have just tried to update the firmware on my original phone and it failed with this message on the phone:

sw rev fail bootloader device 5 binary 4

and in Odin:

<ID:0/004> Odin engine v(ID:3.1303)..
<ID:0/004> File analysis..
<ID:0/004> skip file list for home binary
<ID:0/004> param.bin
<ID:0/004> modem_debug.bin
<ID:0/004> Home Binary Download
<ID:0/004> Total Binary size: 4188 M
<ID:0/004> SetupConnection..
<ID:0/004> Initialzation..
<ID:0/004> Get PIT for mapping..
<ID:0/004> Firmware update start..
<ID:0/004> NAND Write Start!!
<ID:0/004> SingleDownload.
<ID:0/004> sboot.bin
<ID:0/004> FAIL!

Having done a bit of googling I think the bootloader on the phone is newer than the version I was trying to update to so it can't proceed. I had downloaded the latest O2 firmware from this website for my phone. How do I get the updated (version 5?) bootloader?

Apologises if this is a stupid question, only been learning about all this for the last 2 hours or so!