Sounds like your doing everything correct but since it is your first attempt you may not have the feel and are afraid to cause damage. It may not be threaded to to the point of as you turn it screws off. Line up the points to OPEN and with the smallest blade, I do not know if a pin from running bib numbers is too fine will work. I the worst case scenario happens, Chris and I at Polar will take care of you, assuming you live here in the USA.
A glasses screwdriver works well. Much better than a pin.
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