Well there is this:
Primary sources contain no such statements. Byrd’s expedition logs, radio transmissions, and official reports from his 1926 flight over the Arctic and his later Antarctic expeditions contain no references to hollow Earth entrances, polar openings, hidden civilizations, or unexpected warm areas.
• The infamous “secret diary” is not authentic. A text often cited as Byrd’s suppressed personal account, describing flying into an inner world or meeting non-human beings, surfaced decades after his death and is demonstrably not in Byrd’s hand, tone, or known writing style. There is no archival trail for its origin.
• Misinterpretation of a 1947 remark. Byrd made public comments in the late 1940s about the strategic significance of the polar regions, describing them as potential avenues for military attack or rapid travel. A key phrase—often quoted as him saying there was “a land beyond the Pole”—referred to the geographical and geopolitical importance of the Arctic basin, not a literal landmass.
• Operational records show the expected Arctic environment. Meteorological notes, flight logs, and scientific observations from Byrd and his contemporaries match what is now well-established about the polar climate and geography. No anomalous warm regions, hidden valleys, or unexplored continents appear in the data.
• No corroboration from other explorers. Amundsen, Nobile, Ellsworth, MacMillan, and later Arctic researchers crossed the same regions by air and ice, producing detailed maps and measurements that leave no room for the extraordinary features attributed to Byrd’s accounts.
• Fringe interpretations arise from later authors. Most extraordinary claims first appear in 1950s–1980s hollow-Earth or esoteric literature that used Byrd as an authority figure but provided no primary documentation.
Summary by ChatGpt. I shall expand on any of these to which you offer an evidenced refutation.