A safety razor (nice and flexible, don’t try a utility razor) did the trick. Once the corner of the blade is under the glass (maybe 1/8 inch), a pick will slide right in under the blade.
Also, a helpful hint for using the iOpener at altitude: unless it has cooled to nearly room temperature, keep your reheat to a single run of 30 seconds in the microwave. I waited more than double the recommended time (around 25 min.) and the fluid started bubbling in the second 30 seconds, rupturing the iOpener.