sechel, learn basic Rashi on the Gemara in Sanhedrin. He says that the Gemara doesn’t mean Mashiach can come from the dead, it means if you think Mashiach already came.
The Rambam, in Melachim 11:3, says that Mashiach will arrive in a natural way, without miracles, similar to Bar Kochba. He further says that Mashiach will not perform any miracles, and will not resurrect the dead.
