Demo mode on and system does not stay on

are you sure it's not just going into demo mode after you turn it off? There should be a button on the remote to turn on/off demo

http://www.retrevo.com/support/Panasonic-SC-AK100-manual/id/356ag917/t/2/

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A demonstration of the display is shown if you have not set the clock.

You can reduce the power consumed in standby mode by turning it

off.

During standby mode

Hold down ['square icon'/-DEMO] until "NO DEMO" is displayed.

Every time you hold down the button:

NO DEMO (off)↔DEMO ON (on)

To show a demonstration of the display
Hold down ['square icon'/-DEMO] until "DEMO ON" is displayed.

To get the STR-DE845 ( or STR-DE945 ) out of DEMO MODE - Turn unit on and HOLD POWER BUTTON FOR A FEW SECONDS ...Turn unit off and when you turn it on again it should be reset ...It worked for me.
( Note : You may need to do this procedure before it goes into its actual demonstration of features ... Press and hold the power button immediately when it initially starts scrolling it's DEMONSTRATION MODE message . )

while the system is on press and old the demo button until the demo plays (while system is on) press and hold the demo button again to turn the demo off. and to preset the stations press tuning mode so it goes to preset the press set select what number you want the preset to be and press set again to save it.

Set the time via the remote control and this will stop the demo running every time you turn it off.

I Have managed to solve my instant turning off fault. As its been mentioned before, this is a demo mode fault, heres what I did...

Leave the Unit in standby, and press and hold the "system menu" button you should see the words "demo mode" flash up on the display briefly, at this point press the "set" button to enter demo mode selection finally press the "+" or "-" button to turn the demo mode off.

You have to be quick with the remote buttons when getting into the demo mode, might take a few trys.

I'm not sure if this will fix everyones fault, but certainly helped with mine. Good Luck.

Press the Selection button about 3 seconds
When the Demo On mode appears
Turn the VOLUME dial until Demo Off appears
Press the Selection button again to get out of this mode.
Done.

That demo mode thing is painfully annoying. With mine, I had to hold the 'display/demo' button in for about 1 second and then the words "NO DEMO" appeared. That fixed it.

I have this same problem, just started 2 days ago. Changed batteries in remote and everything - driving me nuts- now i cannot change channel or adjust volume! I powered off TV, took batteries out of remote, turned back on and now still stuck. I think we bought junk!

To stop the demonstration mode
• Press and hold stop (on the system
only) for five seconds when the
system is in demonstration mode.
ª The demonstration will stop.
ª "DEMO OFF" is displayed.
ª The system will switch to standby
mode.