put latest UEFI files on it and tried instant flash
I don't understand. You should have only 1 file on the FAT32 flash drive, the BIOS update file named B85MP42.50, when doing an instant flash through your UEFI settings.
https://www.asrock.com/mb/Intel/B85M%20Pro4/#BIOS
https://www.asrock.com/support/BIOSIG.asp?cat=BIOS8