You might try resetting the processor.
FROM THE MANUAL:
To reset the AV receiver/AV amplifier to its factory
defaults, turn it on and, while holding down the
[VCR/DVR] button, press the [STANDBY/ON] button.
“Clear” will appear on the display and the AV
receiver/AV amplifier will enter Standby mode.
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You might also try inserting and removing the test mic while the unit is on.