FW issue with NSA 320

Hi,

I have the following issue. I have a NSA 320 and I tried to "update" our current FW 4.70 to 4.01 since I read on the manual this was the first FW. I entered the web interface and update menu and I upload the FW and I wait and I see the sysled is blinking on green and nothing happend. I tried the force flashing and read on the exec log file that invalid bootform.

Please help how can I solve this issue.

Thank you very much for your help.

Best regards,

Csaba