the splashscreen is part of the firmware upgrade so you may have a firmware without a splash screen or something different, the only safe way to do it now is to downgrade your firmware to v29 or older then upgrade it back up to v32 but make sure you use a v32 with the correct splash screen you require.

now bare with me on the aux input as my vehicle is an early mk3 range rover but is essentially a e53 x5 under the skin, now from what i have read on forums etc aux input was enabled on later bm53/54 units i think from 2005 on, if you have an earlier unit aux can be enabled on bm54 via a firmware upgrade and the aux being fitted, you may however have a bm53 in your car and i don't know how you would go about it as i'm in uk and we only have bm54's over here, there are also 2 types of bm54 round pin and flat pin, only the flat pin can be aux enabled. we have a company here in the uk called carphonics that do several bm54 upgrades including aux in, bluetooth aux in, aux in via 30 pin ipod cable and aux out for seperate amplifiers it may be worth chatting with them if you do not have an aux enabled unit.