Make sure that headphone detection (Active Noise Cancellation) is off, if on, if something moves the headphones near or outside the earphone, it will automatically turn on. Make sure the headphones are facing downwards when on a surface.

If your software is out of date, this will lead to errors in your device. Make sure that the device and the app, if using, are updated to the newest version.

Make sure that all additional settings are turned off before charging or setting aside for the night.

Make sure Bluetooth connection is off, since reconnections and making left on can drain battery life.
Volume settings can also lead to low battery, especially if you leave it on at high volumes.
Check the case charging settings, if the charging case itself doesn't have sufficient battery to charge headphones, it won't charge the headphones.

Replace or switch your USB cable to see if the issues are with the charging method itself.