Hey Sajeev,
Thanks for giving my assembler a try! Given that you are using Windows, have you followed the setup instructions for getting DFU working on Windows? Dealing with USB devices on Windows can be a bit of a pain.
Secondly, when you mention hex output, are you referring to the Intel HEX format? The assembler doesn’t currently support that as an output option but it could be something I add in the future.
Best,
Andrew D.