Ok, I replaced m300a.bin with clppa.bin. But nothing has changed. When I remove the clip+ from the PC I see nothing on the display except “Plug USB cable”. Then after turning it off and on again, I see:
"Loading firmware
File not found"
and then again, “Plug USB cable”.
I know that the owner had loaded Rockbox on this and then botched an attempt to remove it. I hope that might help someone suggest a solution.