Well, download the required firmware files and folow the tutorial in the first post (at the beginning of this topic). You should be able to flash it to that firmware then.

Using XS++ on CID53 DB2020 phones will not help you. It still doesn't have the support for CID53 flashing. I mean the new version should have it, but the current one does not. So JdFlasher is the only tool that can help you flashing your phone for free.