This is a hoax. It has many red flags. They were rejected by several journals and started their own journal. The press release that was sent out to the public, which bypassed the normal peer review process, brought it to the attention of all. (In this instance, peer review rejected it.
It is possible that they have submitted the paper to legitimate journals, which suggests that this might not be an active hoax but an honest mistake. Although it is possible they are right, it is very unlikely. Cold fusion must be proved. It is important to eliminate all possible sources of error. They also miss key evidence that would be expected to be found.
It seems that having founded a journal with real sounding content, possibly for the purpose to fool people, has helped to elevate it from “possible honest error” to “probable fraud”.