Similar problems for me. 2.5 days ago my Blaze screen went blank with no response to any of the side buttons. It was still functioning since I could see the sync' data on my mobile. Forced a reset on the Blaze which restored the display. However, it stopped tracking HR from that point onward. Called customer support and did as instructed (updated mobile app to latest version, forced reset on Blaze, toggled HR on Blaze device, but no change. Have not had detailed sleep stages data nor HR data for last 2 days. Since this started I have also noticed a drastic drop in battery charge life. Battery only lasts 14 hours before complete drain. HR green lights flickering super fast. I called back customer support whose only resolution was to replace the Blaze (at a 25% discount). Your problem, together with several others in this forum appears common, and likely unresolvable. My blaze is just under 2 years old. I find it totally unacceptable to pay a relatively hefty price for a device that won't last more than a few years. My advice is:
1. If under warranty, push for Fitbit to replace it now before it's too late.
2. If beyond warranty, migrate to another brand that is much more reliable.
Buyer beware.
