Bro, I used a Windows PC.

Formatted multiple flash drives (different manufacturers, different sizes 2gb ~ 32gb) .. tried everything FAT, FAT32 and even the un-supported exFAT and NTFS.

Still getting the same error.

When I insert the flash, it blinks for like 4 seconds, then stops blinking, then after about a minute the AVR shows 'Error!! 8-05' .. just like it needs another files/copied wrong files.

I copied multiple versions of the firmware from the official website, Unzipped directly to root of USB flash as instructed, still no success.

I just wish if could've bought the EPPROM for the firmware and de-solder and re-solder it myself.