The sun should never shine on an uncovered primary mirror. The lever is a variable speed control for the shutter drive motor. If this doesn't help, turn the synchronous drive off and try again. The shutter will stop moving when it reaches the correct position. Check safety lock-off switches.
Bottom shutter is opened after top shutter opened, closed after top shutter closed.
Check safety lock-off switches. Check in dome for people, ladders, crane cables near telescope. Check safety lock-off switches. To release the emergency stop, pull the button out. All the buttons must be out before the telescope can be moved.