Question about JBL Tuner 2

I can do both at the same time

I don't think so, I can do both at the same time.

If the battery is completely empty, you must first charge it a little. If you want to start playback while continuing to charge, you must first unplug the radio, switch it on and then plug it back in during playback. For me, it doesn't work to switch on the radio while charging, but it works the other way round :)