Is it by any chance a JP1-enhanced 6131? Check in the battery compartment section to see if there is a JP1 6-pin header installed.
If it is, the previous owner may have installed the extender for the 6131. It will remain installed even after batteries have been removed, and is activated by pressing the power while in PVR mode (the default mode when new batteries are installed). To check this, remove the batteries, press a key, then re-install the batteries. Now press power. If the LED blinks 4 times, the extender is installed and has been activated.
If you don't plan to use JP1, you can do a
manufacturer's reset to wipe it clean. If you will be using JP1, I recommend leaving the extender installed and doing all configuration by JP1.