Because it’s an OEM board, the "manual" you are looking for wasn't really a glossy booklet included in a box. It was a technical service guide intended for the technicians assembling the PC.
A: The battery is a CR2032 coin cell. It is located between the PCIe x16 slot and the rear I/O panel, or near the chipset heatsink. The manual calls it "BAT1." FOXCONN ML194V-0 MOTHERBOARD MANUAL