I just installed a brand new Digi+ on my raspberry PI B+ running Arch linux.
I followed the instructions here: https://www.hifiberry.com/guides/configuring-linux-3-18-x/
I get the following errors from dmesg:
[ 13.610923] wm8804 1-003b: Failed to read device ID: -1
[ 13.617966] wm8804 1-003b: ASoC: failed to probe component -1
[ 13.751021] snd-hifiberry-digi sound: ASoC: failed to instantiate card -1
[ 13.751175] snd-hifiberry-digi sound: snd_soc_register_card() failed: -1
[ 13.751213] snd-hifiberry-digi: probe of sound failed with error -1
Note that I could not complete step 1 of the instructions because there was no blacklist file on my system, I just skipped that part.
Could it be a damaged or malfunctioning unit?
(I observed little signs of stress on the packaging: some pins made marks in the plastic cover indicating the parcel may have been "compressed")