There's not enough information to offer any help.
- We don't have any information about your e53 X5...what is your model/model year/build date? (it reveals what you may already have installed or need to install)
- We don't know what your purchased (what is it's 11 digit BMW part nbr?). There are multiple BT modules. The older ULF modules that have buttons inside the console that are required to pair...then you have the latter TCU BT modules that pair within a 2 minute period when the ignition is turned on. Then there are incompatible BT modules that are used for newer BMWs that communicate over the MOST bus vs the older TCUs that work with your generation BMW and communicate over the I-bus
- There are some BT modules installed in early 2004 that actually do not have BT capability (see info below & note text highlighted in yellow)