Display says Protect , and the unit does not start.

Protet mode is a special diagnostic mode that starts when a fault is detected.

When in protection mode the unit is prevented from starting by protection circuit, so to prevent further damage.

Check the speakers and speakers wiring, a contact in speaker wires, or faulty speakers can send the unit in protection.

Try unplugging power cable for one hour or so. then connect cable back and see if you get rid of protect state. Sometimes accumulation of electrostatic charges inside circuit capacitors can kick in protect mode. In that case unplugging the unit from main for some times can get rid of electrostatic charges, and reset circuits by draining power completely.
If that was the problem, you will not get Protect when plugging back power cable.

If you do all the above and still get Protect, then there is a real fault.

In that case the unit may be disassembled and tested to find the fault.

If that is the case I suggest contacting the manufacturer at the number listed on the owners manual, or asking a quote on repair to a local technician.