Jeffro
Yes the date 538 is impossible because the timeframe is too short for the many events that are described in the first year of Cyrus. One recent scholar who has published on this subject discounts 538 but admits to the plausibility of 537 as a possible candidate and after a lengthy exposition on the subject comes out in favour of a later date which from was 535 BCE.
I have never maintained the view that scholarship supports our chronology. It does not. What scholarship has shown and does show that these dates are controversial with no agreement such as 586 vs 587, the seventy years, date of the Return etc. I appeal to scholarship in order to highlight the simple fact that the claim that WT chronology is so implausible and cannot be right is simply false because there is no universal agreement on chronology. All OT chronology is subject to opinion and interpretation and our chronology is just as credible and valid as any other scheme. Our chronology is simple and Bible based and nothing can detract from that.
The other major problem with your 538 proposal is that you have no ringing endorsement from Carl Jonsson who merely assigns this matter to a footnote in his GTR. His silence or reticience on this speaks volumes.
scholar JW