I understand. This means your Plasma display is not receiving proper communication from the Media Receiver. This can be caused by the two System cables having failed- either internally (bend or broken internal connection), or one of the pins on the cables being bent, pushed in, or not connected securely. Or when you removed power from the Media Receiver, once it was plugged back in, the surge of power being reconnected took out the capacitors in the box- this is a very common issue with these Media receivers once they get on in years.
The first step would be to carefully inspect those system cables, and test each end using a multi-meter, or simply replace those cables.
If the set still does not power up normally, then the Media Receiver box would indeed be in need of service, which is on average a $250 repair. There are 2 capacitors and a voltage regulator in this box that are prone to failure and if you'd like you can use the link below to locate a tech in your area:
Other than that, I'm sorry for the bad news here and wish there were a quick fix.
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