I’m sorry to hear about the app crashing, and the repeated attempts at firmware upload. Some other users have reported the new firmware upload procedure in Android is failing, it seems to be related to the BLE stack in Android 4.4 and 4.3. We’re adding a “legacy mode” button that will do the slow upload like the previous app versions.
More concerning is the crash you’re seeing when you switch to AC volts. If you have anonymous reporting turned on in Android we should be able to see your crash report in our Android developer console, but if you don’t have it turned on please email any information to firstname.lastname@example.org and we’ll try to get to the bottom of it.
If it’s possible to upgrade to Android 5.0 I recommend it, the BLE stack gets a lot more stable. But I’ll dig in to whatever logs you send to see where the app’s crashing.