You will remember Lev Ivanov, after studying the DPI his entire life, finally concluded that it was an aerial phenomenon that killed the hikers. He said "UFO" but without aliens, simply an unidentified flying object.
Kuersten tells us that plasma is considered the 4th state of matter (after liquid, solid, and gas), and that it is highly charged and can do amazing and unstable things. He says that a plasma ball floating over Mt. Otorten, as seen by hiking groups in other locations in the Urals that night, exploded, producing a blast wave and causing injuries and burns. He goes on to give many examples of plasma balls throughout history in many different places and times. The Mansi were quite familiar with these plasma balls, particularly the type where there is a main big ball, which then spawns a bunch of smaller ones, which they called "lanterns." He proposes that one of these exploded near the tent, causing that big flat circle of snow that had melted and then refrozen (which others have suggested was where helicopters landed). He also proposes that one of the smaller balls got inside the tent and exploded on the top of the now-broken ski pole that has puzzled people for so long; it also shattered the lens of the camera that was found in the tent, set up on a tripod. This explosion near -- or inside of -- the tent was what caused the hikers to leave the tent.
He also says that at least 4 of the hikers and possibly 5 were taking pictures of the plasma event, which was so extraordinary that Zolotaryev took his camera with him when they left the tent. He does present these photos in the book, some of which I had not seen before.
Anyway, it's pretty interesting stuff.