when i press cd on radio button it keeps giving me 'no cartridge' i cehck and it

What is your question?

2001 s500 Just got this car week ago from engineer that told me he has own this car for 10years, i check everything (so i tough) i forgot to check if cd was working. I notice that when I press cd (radio) keeps giving me no cartridge? I check and was in, I tried to eject and will not. How do I fix this? I read some info in web, allot of comment about cd cartridge worn out, its known trouble, one suggested removing battery and system should re-boot and will recognize cd? This I am hesitant to do. Any suggestion. OR SHOULD I JUST GO FOR AFTER MARKET BLUETOOTH AND CONNECT TO RADIO?