Polar - Updates for Flow app Android, M400 and V800 users: - Flow app Android release corrects the activity and training data visibility issue which some of you experienced - firmware updates
Polar M400 User Manual
How to Hard Reset POLAR M200 – Restore Defaults / Wipe Data - YouTube
polar flow does not connect/sync with flow app, even after resetting everything. : r/Polarfitness
Tech Review: Polar M400 GPS Running Watch - That Shelf