Sony ht-sl5 switch on then after 10secounds shuts down and protect appears on the display .and cannot do anything with it but turn it off

If your problem is "switch on then after 10secounds shuts down and protect appears on the display .and cannot do anything with it but turn it off"

Then the unit is on protect mode, that is a special diagnostic mode that starts when the unit detects an internal fault.

To start unplug the unit from power for ten minutes, and see if this reset the protect mode, I guess you have done this already.

The first thing to do is to start the unit with nothing connected, if the unit does not go to protection, then the problem was one of the cables or a connected device.

If that does not fix it , there is a master reset , by pluggin the unit into main while at the same time you hold the power button.

If still no luck then the unit is defective and must be taken apart and tested with a multimeter.

You start checking for burnt areas on circuits, cold solder joints and leaking capacitors at sight, then there is need to grab the multimeter and do the real testing job.
When you find the problem you do the soldering.

Naturally this requires a certain experience in fixing electronics, to complete the job usually a precision soldering is needed.

The protect mode indicates that a problem was detected in the final stage of the output amplifier. The unit is shutdown to prevent further damage to either the amp or the speakers. I don't kow the specifics fo your model, but if it has discrete transistors for outputs, the parts cost will be in the $15-$25 range. If it have an AMP pac, expect parts to run in the $60-$75 range.

Dan