As most people have already responded, a starting point is to have a trusted BMW indy take a look, pull any codes, reset the adapter data, and double check the trans fluid levels FIRST. BMW considers a trans fluid "lifetime Fill" which has been translated to mean "life of trans". It died, then that was it's life...so sorry. Low trans fluid levels, clogged filters will provide a multitude of symptoms, some that you described.

One recommendation I would offer, is to service the trans as mentioned (filter, fluid, - pan if necessary, and the wiring seal above the valve body.
Part Number 1 on image below. See Penske Parts Penske Parts - Technical Diagrams - E53 X5 4.4i (N62) SAV
24347588725 SEALING SLEEVE $20.08 Before I would jump to any conclusions on the status of a BMW trans, as multiple people report 80-90% resolution on this process.

Keep in mind the PO may have had this issue and bailed so check the down stream affects on drive shaft guibo and mounts as you do a deeper inspection.

Please report back your steps and possible resolution so other may learn as well. Gee, I think that is why we are on the forum....sorry

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2005 X5 4.8IS
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