Hi, my PreenFM2 doesn't show in any of 3 computers (win7 win10 and Linux Ubuntu) neither as Midi interface or as USB stick when it boots with button 1 pressed.
However it powers ON and works with USB power.
I built it and flashed its bootloader to v1.11 a few months ago with the mini-usb.
I've try with several USB Cable and USB-midi is turned on in system.
Running firmware 2.07.