ASRock H110 Pro BTC+ not booting

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ASRock H110 Pro BTC+ is unresponsive and I've been asked to see if its a bad bios. Able to read the MX25L6473F with flashrom, but I quickly see that in the age og UEFI I'm on thin ice.

Bios is "64Mb AMI UEFI Legal BIOS with multilingual GUI support" and BIOS downloads come in three different flavours (ROM/DOS/WIN) which all decompress to a 128kB binary.
https://www.asrock.com/mb/intel/h110%20pro%20btc+/#BIOS

I've lookded at https://github.com/LongSoft/UEFITool but can't see how to update the flashrom backup with the downloaded BIOS to flash back to the chip. Pointers most welcome!

Also if anyone has something like a service manual it would very helpful!