I'm assuming that you are connecting to your amplifier (B&O?)using the standard 7 pin cable?
It should be labelled "phono" if it's the correct one.If you are using another cable,is it the correct configuration?You can connect using the RCA left/right connectors to another make of amplifier.
If C354 has indeed failed,the sound will usually emerge after the unit has "warmed up",say about five minutes.
C354 is situated centrally on the lower of the two pcb's,and that board is a bit of a pain to remove,as there are loads of plug in loom connections that become disturbed.Take photo's to aid reassembly.
I would replace C351 and 352 also while you are at it.
n.b.make sure that you fit the replacement capacitors in the correct polarity,but if you don't feel confident to do this work,try and find someone who has B&O experience.It would be tragic to damage a nice machine like this
Nick