"Checksum mismatch"
Re-download the file. Do not attempt to flash a corrupt image.

"Device not recognized after update"
Perform a hard reset: hold reset pin for 10 seconds.

Official Status: The developers of Flux have moved on to newer versions and rebrands over the years. The official "Flux" website often redirects to newer clients or different projects. Because B14 is an older build (relative to the current Minecraft meta), official support has ceased.

Where to find the file: Since the official distribution of B14 is largely discontinued or archived, users typically find downloads through: