I love the watch but this is one of those watches with a monocoque case, which means to access the movement you have to remove the crystal. Yep, Annoying! Tissot even puts the key that you need for that operation in the case back. Yes, you don't exactly need to use that specific Tissot tool. You can use a jaw or a lifting tool. No, please don't use a fucking knife. You're going to damage the crystal and the case. Also, I wouldn't recommend a beginner to do that. The chances that you're going to break the crystal are pretty high. Take it to a professional or practise in a different cheap watch first hand before trying in a vintage or more expensive watch.