Started with a cheap unbranded smartwatch that was headed to the trash. Tried open source apps, then gattool, and ended up down a 14-hour rabbit hole trying to figure out why the same watch kept identifying itself as either a C20 or C30 depending on its mood. Turns out it runs on a Jieli generic chipset with multiple layers of obfuscation. Documentation is basically nonexistent. This repo has everything I mapped out — BLE services, characteristics, and the investigation files. Not a formal project. Made with stubbornness, sleep deprivation, and Claude AI. If you have one of these cursed watches, maybe this saves you the suffering.