First, this is a great trouble shooting flow chart. Hopefully it will same a lot of basic questions needing to be asked. The only change I'd suggest to it as it exists, is your very first box should read "charge gun" instead of "chamber round". (If the instruction is "chamber round", the answer is always "yes" if you have proceeded. I'd go with "charge" because that's the action that attempts to chamber round, then the next step evaluates the results of charging.)
Second, I think there might be even more you could add to it, or as a notes with it.
For example, it doesn't contemplate someone attempting to chamber an incorrect caliber round. If someone shoves a Glock mag of .40 S&W in their small frame Glock lower with a 9mm upper, the round won't chamber and your chart has no check.
I'm a big fan of accounting for that level of idiocy. Last time at my FFL, I heard workers chatting about S&W's great customer service/warranty, citing how they fixed (free, 2 week turnaround) a woman's gun after she forced the magazine into it backwards and messed it up. People do unexpected, stupid things. My general guide is "geared to catch mistakes someone recently concussed might make."
Even if you don't account for the real idiocy in the flow chart, it might be a good idea to lay out a list of presumptions necessary for the flow chart to work so a true noob doesn't miss something we all would just assume they did.