After a past experience with the adhesive strips immediately tearing on an iPhone 4, I knew to heat the battery with a hair dryer before pulling on the strip. After heating the battery, I was able to pull the adhesive strip without any problems.
I purchased the repair tools with the replacement battery from iFixit. The tools include a screw driver and three heads none were labeled 3.4 mm. I think the one that fit the pentalobe screws was labeled Y000. The guide should identify the screw driver head supplied by the kit not 3.4mm.