We would like to inform you that replacing the CMOS battery should not affect the boot and POST sequence.
Here are our recommendations:
Test the system out of the chassis on a minimal configuration, remove all memory and look for beep codes. Check for lights and fan activity. If there are beep codes without memory, start adding each memory module individually. If no beep codes, proceed with a BIOS recovery test:
Swap components if possible and if the issue still persists proceed to replace the board under warranty.