Very difficult, broke Watch display.

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The Watch is 3-4 years old, and the battery life was noticeably reduced, requiring a second charge daily.

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While the battery removal and replacement are very simple, removing the display is much more difficult than the instruction video suggests, so much so that I think the video should be replaced with one that fully demonstrates the challenge. While using the Curved Razor Blade to "create a gap between the display and the metal watch housing and then rotate the blade," the edge of the display cracked, requiring a replacement display.

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As noted in the guide, wear safety glasses as the cracked display sent small pieces of glass flying. Take extra care when using the Razor blade as it slips very easily on the metal and glass, creating an opportunity for injury; I kept the watch bands attached which allowed increased flexibility in keeping the watch still and fingers away from the blade. Due to the increased cost of the damaged display, this may be an excellent repair to let an authorized shop perform.