Your motherboard expects a 256KB, 512KB, or 1MB BIOS. If bios41a.bin is the wrong size, the flasher will abort. Solution: Verify your motherboard's chip capacity (e.g., 28F002BX is 256KB; 29C040 is 512KB).
Demystifying bios41a.bin: The Ultimate Guide to the PlayStation 1 System File bios41a.bin