(Though when I tried to use a causal DAG for root cause analysis of an incident at my current company, I was told that I was wasting time and no one cares. But I thought the data I found was pretty interesting and worth exploring.)
In manufacturing there is usually 4 big topics (person, machine, material, method), but there are many variations that can be used.
Trees or other visual depictions can be used too.
The point is to have some sort of structure and adapt it to your needs.
You keep asking "why?" and only want one 'thing' to be 'actionable'... you will raise my frustration level. The root cause is an emergent property of understaffing, poor communication practices and a belief that everything can be reduced to a jira card providing sufficient context and understanding for a diverse audience with different skills and needs.
It's really hard to do RCA when people are blaming themselves. It had to suck to be in that meeting. A really good RCA isn't about finding a single actionable thing, it's about finding our what the root cause of the problem is... which in this case, might have been whatever originally broke production and caused an emergency fix that failed three times.
Often, the root cause is someone made a mistake. You can say there should have been other systems to prevent/review/etc, but the root cause is a mistake a person made. You can '5 whys' it to death, but I made a mistake (or... someone did).
"whatever originally broke production" - in this case, I made a mistake. That mistake wasn't caught until production. Then the fixes were all broken too.
I don't always blame myself for everything, but if I've made a mistake, I'll own up to it. For me, it helps me be aware of what I can do to avoid those in the future. This may or may not be some rca-checklist other people can refer to, because... it's not 'actionable' to anyone but me.