I've had this happen to me a couple times as my torque wrench just didn't seem to stop...It should be 14nm for the bolts by the way. I usually do 12 for safe measure and have had no leak problems.

If you can't grip them the only way to remove them is by using an EZ-Out. Be careful and cover all areas so no metal shards get into the engine. It's gonna be a pain...goodluck!

I suggest buying a full new set of valve cover bolts too.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k