So you're not a total newbie

go on with the serrated pins, if you can pick a cisa or a viro I'm sure that an HAS lock is not a problem for you. Just keep the tension light and try to remember which pins reset the lock so to avoid to push them too many times when you start again.
If after a couple of minutes the lock won't open you probably overset a pin: completely release tension and start again.
Cheers
