There is a rattling sound inside watch case when it vibrates as if there is something loose inside. This happens a few weeks after my warranty expires (obviously) I typically baby my watch and I've never drop my watch nor put any force on it. From what I've done extensive research on this, it looks like a hardware defect from Garmin itself and in other regions they replace it right away. This is not the case with Garmin Thailand, the repair and customer service ask me to pay $140 for replacement while blaming it on me. It's a shame that watch advertised as tough, durable and most importantly a dive computer which you depend your life on is so unreliable. This is going to be my last Garmin watch
You can find similar issues in many threads,
https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/instinct-solar/286098/vibration-rattle