By the way, if you torqued all the bolts down the same, you likely need all new bolts now. If 5 broke, I'm sure the rest have torsional twist and serious stretch stress.
I would guess the larger bolts would have had to see 40 lbs or better to break, unless you've got some poor grade bolts there instead of the oem parts.

Also, it usually takes more than 20 lbs to remove a bolt torqued to 20 pounds. Remember never torque bolts that are not lubed, at least with oil.

Give up on your torque wrench until you are sure it is accurate