Change starting image on Enigma2 decoders

I got a Zgemma H7s, and I had a problem flashing images, so it didn't boot anymore. How to resolve? In this case the decoder stop at 49, when starting. At this point you should log in with SSL or FTP. I prefer FTP due is simpler. Login show me the directory tree on decoder. I go to /boot. When using OpenATV like I do, there are some files:

    STARTUP_LINUX_1_BOXMODE_1   STARTUP_LINUX_3_BOXMODE_12
    STARTUP_LINUX_1_BOXMODE_12  STARTUP_LINUX_4_BOXMODE_1
    STARTUP_LINUX_2_BOXMODE_1   STARTUP_LINUX_4_BOXMODE_12
    STARTUP_LINUX_2_BOXMODE_12  STARTUP_LINUX_3_BOXMODE_1
    STARTUP

STARTUP is the file that choose the image to start. It should be overwritten copying one of the others (with the image working).