Puck Displaying "Bad RTC" or "CMOS Checksum Bad"
Symptoms
When powering on a Puck, a warning screen with the message "Bad RTC" or "CMOS Checksum Bad" is displayed.
The Puck may lose its date and time settings when powered off, and revert to an earlier date and time when powered back on.
Explanation
Pucks use a small internal CMOS battery (also called a BIOS battery) to store date and time information and BIOS settings while the console is powered off.
These symptoms indicate that the CMOS battery has become drained. To resolve these issues, the battery should be replaced.
The exact battery needed depends on the specific revision of Puck. See the following articles:
The image below shows where the CMOS battery is located in a Windows 10 Puck. The SSD must be removed to access the battery.
