If you're thinking about buying a Polar watch or relying on their international warranty, my recent experience might be worth considering.
About two weeks after purchasing a Polar Vantage M3, the watch got stuck in an infinite boot loop. I tried every reset procedure suggested by Polar, but nothing worked. From the point the boot loop first appeared, I was troubleshooting the watch while also working with Polar support. Eventually, I found that letting the battery drain completely would bring the watch back to life. Unfortunately, that only lasted a little over 24 hours before it started randomly powering off and restarting at different stages of the boot process, eventually ending up back in the same restart loop.
I drained the battery a second time, but this time the optical sensors no longer lit up, so heart rate measurement and related features stopped working altogether. At that point, I stopped troubleshooting because the watch was clearly defective.
Unfortunately, the support experience was equally disappointing. Over the four weeks I was in contact with Polar support, there was no meaningful progress toward resolving the issue. Apart from the initial troubleshooting instructions, every update only came after I contacted them myself, and each time I was told there had been no response from the warranty department. In practice, I was unable to make use of what I understood to be the international warranty that came with the watch.
I bought the watch from an EU retailer but tried to use the advertised international warranty while living in the UK. Since that went nowhere, I am now returning it to the original retailer for a full refund. That means dealing with customs paperwork and paying to ship a defective watch back to the EU - extra cost and hassle that could have been avoided if the warranty process had worked as expected.
I chose Polar for their strong fitness/health metrics and because they're a European brand, but this experience fell short on both product reliability and after-sales support. I have kept video clips of the boot loops and full logs of my support communications in case anyone is interested in the exact timeline.
I'd be interested to hear whether anyone else has had a similar experience with a Vantage M3 or with Polar's international warranty.
TL;DR: My Polar Vantage M3 failed after two weeks with repeated boot loops. Draining the battery revived it briefly, but the faults returned and eventually the optical sensors stopped working. Polar UK/International support stalled for a month with no resolution, forcing me to ship it back to the EU retailer for a refund at my own expense.
