What can short-circuit in the induction cooker (automatic machine trips)?

Hello. There is a hob Fagor 5ift-22 s. 2 comforts at her induction, 2 usual with heating. Symptoms are as follows: when you turn on the induction immediately knocks the machine. When you turn on two other comforts, everything is fine. What was done: PWM replaced, power transistors. The board is the same IND5G-CF power supply. Conventionally, the board can be divided into 2 parts: the power part, which controls the comforts, and the auxiliary, which controls the control board, which is connected separately. There is also a third board, which is only responsible for comfort with heating elements. The control board is powered by auxiliary low power. So, to turn on the comforts of induction, the control board must supply 12V to the relay, which closes the circuit between the phase and the diode bridge. I cannot tell you the model of the bridge now. He was soldered separately and called by the tester, everything is fine with him, but I'm not 100% sure. The question is as follows. If this is not a diode bridge, then what else can be closed after it? After the bridge, all the diodes rang, power resistors, everything is ok. Thanks in advance, and if I didn’t write something correctly, please correct.