How exactly do I charge the M5 Cardputer, and does it come with a built-in charging indicator? I'm curious if there's an LED light or screen notification to show when it's charging or fully charged. Also, what should I look for to ensure it's properly connected to the USB-C cable, and are there any recommended practices for safely charging the internal battery? How long does it typically take to charge, and is there any way to monitor the battery level during use?