2004 euro 3? Volvo S40 1800 Petrol

problem occured yesterday with radio
I turned it off and it wont turn back on

All the rest of floating dash equipment works

Checked fuses inside all ok

has anyone had same or similar before i go to dealer again

(if i have luck its usually not the good kind)

just had to replace all exhaust and cat - cat made up solid restricting revs to 4kmax (55k on clock)

now i am getting black smoke and using a fair bit of oil