After resetting the BIOS, you can set SATA back to RAID (the RAID info is on the HDDs, so no risk).
Yes, try clearing the CMOS. Check also all power connections. Does the board require a 4 or 8-pin ATX power connection? Test the board outside the case and start it by shorting the 2 pins corresponding to the case power switch (not by using the button on the chassis). Remove the reset, the power switches, the HDD led connectors while testing.