btcflash: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/btcflash - from package: dvd+rw-tools

You may install the required package with command apt-get install {package}

Error in other languages:
btcflash: bevel nie gevind nie
btcflash: comandă negăsită
btcflash: comando não encontrado
btcflash: commande introuvable
btcflash: command not found
btcflash: käsku ei ole
btcflash: không tìm thấy lệnh
btcflash: komanda nerasta
btcflash: Kommando nicht gefunden.
btcflash: kommandot finns inte
btcflash: komut yok
btcflash: nie znaleziono polecenia
btcflash: níor aimsíodh an t-ordú
btcflash: no se encontró la orden
btcflash: no s'ha trobat l'ordre
btcflash: opdracht niet gevonden
btcflash: parancs nem található
btcflash: perintah tidak ditemukan
btcflash: príkaz nenájdený
btcflash: příkaz nenalezen
btcflash: команда не найдена
btcflash: командата не е открита
btcflash: 命令找不到
btcflash: コマンドが見つかりません