Just for reference, I could indeed simply reflash the squeezeliteML.bin binary mentioned in Multirooms with SQUEEZELITE with ESP32 MUSE PROTO
screen /dev/ttyUSB0 115200
nvs_erase_wifi_manager
restart
Wait a bit, then
esptool -p /dev/ttyUSB0 write_flash 0x0 squeezeliteML.bin
(not sure if the nvs_erase_wifi_manager and restart steps are needed though.