This just started happening to me too... the morning of my first half marathon (ah!). My FR235 completely reset overnight when it was charging. Took forever to get a solid GPS signal outside to correct…
Your watch might be defective. It should not reboot by itself, no matter what. Contact garmin support.
Your watch might be defective. It should not reboot by itself, no matter what. Contact garmin support.
I have been having this problem on and off for probably 2 years. The other symptom, like Olivia noted, is the watch screen showing the Garmin logo, and gradually fading out. The watch then appears to try to restart several times, with a restart-beep each time, until finally it succeeds. I usually lose about one mile when this happens, so I guess the average cycle is about 5-10 minutes. Another thing: it only seems to happen during particularly sweaty workouts. So... maybe related to the charging/data contacts?
I have lived with it for a couple of years, but now it's been happening much more frequently, two days in a row this week -- not cool. The watch still works fine otherwise, and I'm not keen to upgrade. This issue aside, kudos to Garmin for nailing the product back in 2015, and still selling it 6 years later!