Try a hard reset first . . . easy and free and sometimes works.
Hard reset is the most probably solution and costs nothing.
For whatever reason, it is not uncommon for the radio speakers to quit after either a battery change out or an alternator replacement.
It has something to do with removing the power from the computers before the electronics have gone to sleep.
Then when re-powered up, something in the infotainment software is messed up and sometimes lots of red or yellow warning lights go on as well.
The fix is surprisingly enough, to again remove all power from the vehicle and then as below do the hard reset.
Also before you disconnect the battery, make certain all has gone to sleep.
Also roll the drivers side window down first before you de-power; while a silly concern, I am always afraid of somehow locking myself out of my 3 when fooling around with the electrics.
Hard Reset Instructions
In brief, to start the hard reset process, open the hood but close all doors and let your 3 go to sleep - no radio display etc and no key in the ignition. This will take a couple of minutes and do not open any doors until the reset is completed. (I find that it is often a good idea to have the driver’s door window rolled down and the key in my pocket whenever fooling about the vehicle.)
Also when I play with a car battery, I remove any rings I have from my fingers, also my watch.
Disconnect the ground battery terminal from the main starting battery.
Disconnect the positive battery terminal from the main starting battery.
The reason for this order is if a wrench or loose battery cable ends grounds to the body, no arcing or other bad things happen.
(I assume that you only have one battery in your 3. If not, disconnect the others as well and leave them disconnected until after all is done.)
Connect the negative cable end to the positive cable end. (
NOT the battery.) To do this, you will need a short length, (a foot or so), of light gauge, (14 to 18 gauge AWG, insulated stranded copper), wire to span between the battery cable ends as there is not enough slack in the positive and negative battery cables for the ends to touch each other.
Hold all together for about a minute or more, (at least two minutes), as you are discharging memory modules within the engine computer and elsewhere. Then it is suggested you then just let all sit disconnected for say ten minutes, (minimum five minutes), prior to commencing to put the battery cable ends back on the battery posts per the following order.
Reattach positive terminal to the main starting battery positive post.
Reattach negative terminal to the main starting battery negative post.
Start engine and hopefully none or at least fewer warning lights and the radio when turned on plays music rather than being silent.
Reset time on the radio - note that the station presets are still there as not everything is erased. Nothing much else needs resetting either.
You can also now connect up the other batteries if you have a multiple battery setup.
This is a link to a thread in disco3 re the hard reset procedure.
http://bit.ly/14WXXR1
http://www.disco3.co.uk/forum/topic19547.html
This is a link to a thread on Disco3Club re the hard reset procedure.
http://www.disco3club.co.uk/phpbb/viewtopic.php?f=67&t=3374