Cordial greeting, friend, the ideal thing to do first is to verify that the speaker cables are not short, since it is a possible cause of this anomaly, after checking the cables, another cause may be some of the speakers are short, Therefore, a test is to have the amplifier at a closed volume, disconnecting all the speakers connecting the equipment to the voltage network and turning it on to see how it behaves, if it is still in protection mode, it may be due to damaged audio outputs from there a required technical review to diagnose if there is an internal problem in the amplifier, more surely in one of its outputs.