Download HTR530 Service manual.How to measure voltages?(a)connect the black probe to the heart sink via acrocodile clip. Heat sink can be found easily if you are looking for 12 power transistors.(b)the red probe can connect to any interested points,for example, the POFF (see video1)Check voltages first: POFF(must have. And check 3 components circled in blue see video 1 the last measured voltage) ,10VS (must have)and 12V and also the MPowerd voltage (see video 1) Video 1 shows the MPowerd voltage The lst measured voltagethe - MPowerd voltagemust be ZERO when the amp is switched ON.. Are these voltages present?If so, check reset or you can replace them directly (circled in yellow See video2 and video3)Plug the amp, to see if it is working.If not ,replace 3 components circled in red.If not working again, you can replace the crystal X701,a component 6 MHz, not easily damaged (see video4).If also not working, CPU is torn out.