The iOpener worked for me - once I got the expectation right that it was going to take a while.
Went through about 5-6 cycles of:
* Heating for 40 seconds (1100W microwave); applying to phone for 2 minutes; heating for 30 seconds; applying to phone for 2 minutes; allow to cool for 10 minutes
Could probably have done with one more cycle to get glue even more sticky TBH but when it lifted it was obvious.
