Would be interesting to know if it works fine with previous official firmware 0.110 ?
It's possible that editing env with the previous beta make things unstable with 1.0.
1. Can you rename the "mix.dlf" on the SD card (mix2.dfl or something like that, it won't be read anymore)?
That's the default mixer that is loaded.
Rename and not delete in case you want to get it back.
2. You can copy mix.dlf from
https://github.com/Ixox/preenfm3/releases/download/v0.105/pfm3_SD.zipif you want to have some sounds loaded when you turn on your preenfm.
3. If that's not enough :
On Your SD Card : rename "pfm3/" into "pfm3_old/" and copy the content on your computer to make a backup.
Then put he "pfm3/" folder from the zip above.
4. An other idea (i've never seen) : corrupted firmware.
No worry, you can ALWAYS flash the firmware. From the pfm3 bootloader or directly with DFU mode.
But if that's the case, you should use an other SD card.