No home theater sound

Protect mode will kick in whenever a fault is detected.

You get the unit not powering up, and sometimes you hear a clicking noise, that is the protection switch that keeps shutting down the unit.

Causes that can start protect mode are:

Electrostatic harges on internal circuits.
Leave the unit unplugged for power for one hour or so, this will allow discharge.

Bad speaker wiring.
Check speaker wiring, try unplugging and plugging back, or start after removing one speaker at the time.

Internal fault.
Internal fault is the natural cause for protect mode. If all the above did not work, then the problem is a blown component or an internal fault. In this case the unit must be taken apart , tested and repaired by an experienced person.
If the unit is less than one year old, or if you want to get service, call Sony at the phone number listed on the product documentation.

Regards.