Up2Stream Mini stuck in boot

Hello everyone,
I’ve already finished several builds with Arylic hardware without any hassle.
Today I got another Up2Stream mini and out of the box it is stuck in boot (white LED flashing fast) , Bluetooth connection works. Reset did not fix it.
It is powered via a step down converter @ 5V/0.8A.

Any suggestions highly appreciated!

Thank you very much,
Peter

Almost the same problem. Arylic S10. Connects to Wi-Fi, can listen to Internet stations, can listen to music from a PC via Foobar2000. The white LED blinks very quickly, then stops, then starts to randomly decrease or increase the volume! And then the S10 just reboots with a complete reset of the settings and you have to reconnect to Wi-Fi. In Bluetooth mode, the volume also randomly decreases or increases. What’s the problem???