You'll need to locate and pull the unit that is BM54 therefore it could be taken or sent to a repair website.
The real BMW BM54 repair is usually so uncomplicated the unit may be returned for you on precisely the same day it is received, or done in a few hours ( in case you take it in to a repair centre yourself) to be picked through to the day you drop it in.
The BMW B54 radio unit is created by a company called Becker, whose high class audio has been keeping BMW and Range Rover owners (among others happy for years. You'll find a unit that is BM54 in the BMW 3 series; the auto electrician BMW X5; and some Land and Range Rover models. Your owner's manual should inform you what version of unit that is BM54 you have in your own car.
The BMW BM54 repair begins with fault analysis - so that you need to tell your engineer what's wrong using the unit. Common faults in the BM54 include reduction of total loss of audio sound to one or more channels; or just some of the speakers working. Be aware that simply the speakers in a single area of your vehicle are flawed, or if one of your loudspeakers is not faultless, it could not be the BM54 unit at fault but wiring inside the doors.
You can have your BM54 unit before you send it away for the BMW BM54 repair, assessed for faults in situ. It is best to do this because otherwise you won't know for sure that it is the unit itself causing the issue. And obviously if that unit is sent by you off with no problem,, it's going to come back not desiring fixing and also you'll still have that problem - plus you'll have needed to pay the BMW BM54 repair center for its time.
If you are not sure where to get a BM54 checked before repair, you can request the centre to which you're sending it to do a full BMW diagnostic check on it before they begin to fix it. This means you'll pay no more than you would if you had it checked everywhere else - and if the BMW BM54 repair is not wanted, you won't have put yourself out of pocket in any way.
Every BM54 unit is located under the spare tyre - normally in the boot well, in a somewhat different place. For directions on removing the unit that is BM54 before the BMW BM54 repair, refer to sites or have a look in your manufacturer's guide. When you have some questions contact the business that's going to do your diagnosis and repair and ask their advice.