Does anyone know if a CD player/radio from a 2010 S40 will work in a 2011 C70? I have one and want to replace the one not working in my C70.

 

Which part? the CCM with the controls on it, the ICM with the display, the media player with the cd player in it - or all of it? Note each page has a SW on it - indicating a software download is needed to make that module work. So generally swapping modules does not work. And you can't reload software into used parts using VIDA, only new parts. Xemodex can make used parts work sometimes.
There is also an external amp, the AUD module that supposedly requires software also.
A company such as xemodex fixes all three of those and might have a direct answer to your question

https://xemodex.com/us/product/volvo...module-repair/

 

It is just the CD player, Part 1 in your diagram. The radio works fine.