Surely a transistor of one of the channels has burnt and it goes into protection mode, they are checked and the one with continuity is the burnt one, the transistor pins can be cut and it will start again but without that channel. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Aj_1SKS06Yc.html
