HELP! Problem with mtkflash & SAMSUNG SN-324F

I have a combo SAMSUNG SN-324F and I have tried to update the firmware to the U204 update, but since I finished the updating, my laptop can not find the drive.

I have used mtkwinflash, in order to flash an older firmware version, but I have obtained the following message:

ERR: fail to identify the flash type.

Any suggestion, please, I’m desperate.