Oh, it is the DG module that has the micro on it, and it is the service mode.
One problem I've had is figuring out how to deactivate the service mode, because the exit command isn't written out too well in the service manual. They could have done a better job there.
But a phone call to panasonic always seems to correct the problem.
Panasonic will ask me the model number and the serial number, so if you can get me BOTH, I would appreciate that.
As for the ACTION button, it's most likely the OK button in the middle of the arrow keys.
Here's some other possible Service mode deactivation keys --
Try actually activating it first, then try deactivating it. I know the service deactivation mode has always been a pain to do, they just need better technical writers for that part.
Simply unplugging the TV or pressing the power button for 5 seconds has never fixed that. You have to HOLD DOWN a button on the remote, and the volume button, then it switches over to the module check page, with the OK listed. Then you can turn it off.
You may want to try the OK button on the remote and the power button on the TV for 5 to 10 seconds to see if the CHK message disappears and you get the module OK page....
Then you can hit the power button again.
If you have any questions, just ask
Tips are greatly appreciated !