Why is the program not found?

Question

linux

What is the reason?

Answer 1

./balong_flash
./shows what to run from the current directory.
If it doesn't start, thenchmod +x balong_flash

Answer 2

What is the reason?

On linux (and other *nix* most likely) the current directory is not included in the search path for executable files so as not to cause trouble.
Specify the path through ./(0 directories above) forcibly, or the full path from the root, or transfer/copy the binary to any directory included in $PATH.

Answer 3

Judging by the extension, this is source code written in C. Try compiling it with gcc