With M0, we still have small problems to fix, features to improve and new things to add. But it unfortunately comes to distribution of time, since our software team is split between new product development, updates to M5s and updates to M0.
We are in the world of software development only for very short time and unfortunately it gives us some problems when it comes to timing of new product releases and software updates, which significantly showed in our production during 2018. Especially considering discontinuation of wide range of players from previous generation, that left our product range very limited.
With Bluetooth, apart from apt-X Low latency, there will be always some delay. Then it's up to you system on your phone or computer, if it automatically or at least manually can deal with it.
Likely battery failure. How so that your device is no longer covered under warranty?