but im just copy pasting :-/hi, in my case the problem was an error in writing the ms-dos command
c:\KFFirstAide64>fastboot -i 0x1949 flash bootloader otter2-u-boot-prod-10.2.4.bin
target reported max download size of 486539264 bytes
error: cannot load 'otter2-u-boot-prod-10.2.4.bin': No error