Killed boss before i was meant to and glitched the "Where Angels Fear To Tread" Main quest.

Before i was directed to by the main quest line I climbing picked my way through the gaps above the Sylvans Cradle site of power and got passed the locked door once completing the site of power, i can return to the main quest line and complete all the way to the kill boss quest which has become incompletable due to alreading kill him when i broke the site before.