How do I troubleshoot when there are multiple faults at once?

You can troubleshoot most problems now, but multiple faults at once send you in circles, because every test gives you a confusing answer. That is the hardest situation in troubleshooting, and getting turned around in it is not a failure of skill. Two problems hiding each other would confuse anyone. The circles happen when you assume there's one fault and the readings don't add up. The way out is to stop trusting the whole picture and isolate. Break the system into sections and test each on its own, so one fault can't mask another. Fix what you can confirm, then retest from scratch. Clearing one problem often makes the second one suddenly obvious. And with the dangerous ones, slow is the fast way. When a fault could hurt you, there is no job worth rushing into. Next multi-fault call, resist the urge to solve it all at once. Confirm and clear one fault completely, then start fresh on what's left. One at a time is not slower. It's the only thing that actually ends the circles.