Security settings have been strengthened in the latest BIOS versions (since v.3.50), and the modified BIOS can be flashed with the SPI flash programmer only.
Is it possible to flash directly from 3.40 to 4.80? Their site (ASRock's) says you have to be on 3.50 or later, but is there really any reason for that?
Fixed, https://forums.mydigitallife.net/threads/award-ami-bios-mod-requests.5863/page-3068#post-1440403
SLICs are backward compatible https://forums.mydigitallife.net/threads/oa-2-x-slic-oemcert-collection.5952/