Believing that Rebbe is Moshiach Are decompressing some halakha?
This is a very controversial question, and it is not for discussion in this forum. However I can give you some sources to look at Rambam -Melachim 11-3,4, 12-2, that part of believing that the Moshiach will come is that he will be a live person that hasn’t died (not that he will die and come back), additionally the Rambam says that the messiah will force ALL of the Jews to return to H–shem, will wage wars, etc. Also see Rambam Igeres Taimon, about the dangers and calamities that befell Klal Yisroel as a result of their believing that a particular person was the Moshiach. Additionally, See the book “The Eye of the Storm” written by Harav Aharon Feldman shlit”a chapter 22, 23 that an English book Written by Professor David Berger Called The Rebbe, the Messiah, and the Scandal of Orthodox Indifference.