Certain arcade boards, test equipment, and secure terminals use volatile RAM to store decryption keys or firmware, kept alive by a small coin cell. If this battery drains below a threshold voltage, the memory clears and the hardware deliberately bricks itself to prevent tampering or reverse engineering. Replacing them requires carefully applying parallel power to the circuit before removing the old cell.
Don't just pull the coin cell on that Capcom board, it's a suicide battery and you'll wipe the decryption keys.
Always measure the voltage of a suicide battery while the system is off; if it drops below 2.8 volts, it is time to solder in a replacement with a parallel power supply attached.
Related terms
Battery-backed
Describing a volatile memory or real-time clock circuit that uses a small local battery to retain data when main power is lost.
Volatile memory
A type of data storage that loses its contents immediately when power is removed.
Bricking
Rendering an electronic device permanently inoperable, usually through a failed firmware update.