I have found a voltage beside the southbridge on the test solder point J4A1 where a 3.2Vdc pulses to 2.4vdc on standby and...

I have the same issue but mine has the shut down beep also. I have found a voltage beside the southbridge on the test solder point where a 3.2Vdc pulses to 2.4vdc on standby and when you start up it drops to zero and pulses to 2.4 then shuts down. I can’t find where the voltage is coming from. Unsure if it’s directly from south bridge or if It may be another component that is making it do this. I’ve tested all round but can’t find it. Any help would be much appreciated

Did you ever get to the back of the problem? I have the exact same issue. Do I need to reball the APU? Thanks