Re-start the unit by holding the Ring until you get to the menu, then swipe right to “Power Off”, click the ring to select and then click on “Yes”. Hold the ring for two seconds to start.
The pads auto-calibrate on startup to the pressure currently applied to them. If you switch the unit on with something resting on some of the pads, that calibration will result in those pads being less sensitive. If the unit is switched on while upside down on your lap, the pads pressed on your legs will be less sensitive, requiring a hard strike to trigger, while pads that were just upside down will then be hyper-sensitive. A restart will solve this as the pads will then re-calibrate.
There have been some reports of Lumens with a battery apparently slowly draining while stored in it's backpack.
Switch off the unit before storing. However, this is a temporarily workaround, as we have a firmware update coming soon which will prevent this from happening.
Your Lumen will remain on while you are actively playing it (it's detecting pressure on the pads). If it is still on when placed into it's bag, any slight pressure from the bag padding may cause it to stay awake, using the battery unnecessarily.