Welcome to the forums, newcomer!
By customized, can you elaborate? Was the motherboard part of a prebuilt you'd purchased?
I have an MSI B450 GAMING PLUS MAX motherboard.
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The BIOS version that is built in is E7B86AZ1.HQ2
Are you sure about the make and model of your motherboard?
https://www.msi.com/Motherboard/B450-GAMING-PLUS-MAX/support
Since I don't see that BIOS version on the product support page. If your motherboard was provided as part of a prebuilt, then you might want to avoid tampering with it since a bricked motherboard would mean you going out to have to buy a new motherboard/BIOS chip and effectively losing warranty on your prebuilt if it was recently purchased. I'm merely going by an assumption.
If you've got the make and model of the motherboard correct, then you can follow through this guide;
View: https://www.youtube.com/watch?v=cU7ZMmSmu20
but please be wary of the possibility of losing warranty on your board.
Mind sharing the specs to your build like so:
CPU:
CPU cooler:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:
include the age of the PSU apart from it's make and model.