Well, try it counterclockwise because BOTH bolts are right-hand thread. You just tightened it down.
BTW, be careful when installing the new crank arms. Apply grease (debated topic, I think you should), and tighten it down super hard (check torque spec and try to abide by it. LOTS of torque needed). If it loosens, the taper will round out and you're back on square one.