what firmware did you try to flash? Normally, I would expect the flasher to refuse working if the firmware does not fit the drive.
I guess, you have already read the Read First article about How to flash firmware?
Go to Dell support website, and search for TS-L632H. D400 and D600 firmwares come with a DOS flasher. Extract the flasher and follow the instructions given on Dell website in order to flash original DE04 firmware (of course you have to change the command since you don't want to apply 632H firmware on your 632D).