Ensure your panel resolution is exactly 1366x768 . Installing firmware for a different resolution (like 1920x1080) can result in a distorted or black screen.
Websites like Kazmi Elecom or Softwarezone.ga often host large collections of TV software. Download P75 338V6 1366x768 Major part5 rar
Check the LCD/LED TV Software groups on Facebook where users frequently share Google Drive or 4Shared links for specific board numbers like the P75-338V6. Important Installation Notes Ensure your panel resolution is exactly 1366x768