what actually happen when the headless flying horse got its head?

indy ve just installed the head and that things said ready for his command. it flew away....cutscene suddenly freezes for a while (bug i believe).
when the things back to normal..indy can walk out through the opened door back to main area but the horse dissappeared

where is the flying horse?
why the small floating electric guard doesnt attack indy as usual?
last but not least..WHAT I VE SUPPOSED TO DO??????

When you install marduk's head on the horse it should walk out into the main area between the two large yellow vice things near the control panel that Turner used at the first. Try activating the control panel yourself now with the part you got from Turner and see what happens.