Almost on the day 2 years after receiving my FP1 my battery started to deteriorate. Most marked symptom was a very fast drop from 15 % or thereabouts to next to nothing (warning & shut off). No signs of bloating.
I followed the instructions for resetting the battery described in Stefan’s post. This finally killed the battery (charged from 1 to 4 % after three hours with phone shut off).
Thankfully I had ordered and received a spare battery a few months ago. The new battery seems to work just fine.
Im not particularly disappointed that my battery wore down after two years - batteries may last longer, but also shorter. But I will definitely order another spare while they’re avaliable 
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