USB Debugging option greyed out

Question

I have an LG-E405 phone running Android 2.3.6.

I connected my phone with a USB cable and selected the mode as Charge Only.

Now when I try to tur

Answer 1

Just ran into this on the LG Rebel LTE (LGL44VL). As other answers note, you need to change the USB connection mode to PTP. But my phone's control panels were different from stock Android and didn't have such an option.

The option was hiding in a notification that appeared when I plugged the phone in. I had to open the notification tray and tap a notification labeled

Media Device (MTP)
Tap here for more USB options