I struggled with RICE
for some reason. Couldn't get any computer I have (Windows 7 and 10) to recognize it, swapped tx and rx just in case, just could not get it to be recognized. I don't mind pulling out the card though to do stuff manually.
I tried making all 4 files (boot.wav, boot2.wav, boot3.wav, boot4.wav) the same recording I want it to play inside of bank1 (which I assume correlates with "bank=00" in the prefs.txt file?), reformatted the card, copied all files in one operation, and I still get the beep. Replace with the original files and it works fine.
Could it be the file type is somehow not working properly? I'm making sure to export the audio from Audacity as .wav, 22050Hz, and 16bit. I uploaded the file to http://hattmonkey.com/boot.wav
if you want to examine the file directly just to make sure I'm doing it right.