Dunno what the key looks like for the E38, but these E39 links may provide useful hints for replacing the key body if yours is similar:
- How to replace the old-style BMW E39 square key battery (
1) (
2) (
3) & how to replace the rubber key pads in the old style square keys (
1) (
2) & opening, charging, recoding, & battery replacement (
1) of the new-style diamond key (
1) (
2) (
3) (
4) (
5) (
6) & how to recharge off your BMW and how long a BMW key will last in the drawer before it needs that off-the-car recharging (
1) & converting the old-style square key to the newer diamond shaped key (
1) & the details on swapping the BMW diamond key transponder (
1) & proper diamond key initializing (
1) (
2) & what to do if your key is locked inside your bimmer (
1) & a description of the various types of BMW Remote, Illuminated, Spare/Wallet, & Valet/Service keys (
1) (
2) & a list of diamond key EWS, FZV, & DWA functions (
1) (
2) & all about the 10-key limit to programming your own keys at home (
1) & a description of the ignition key ISN (individual serial number) ten-second rule (
1) & what to do if you lost your only diamond key (
1) or what to do if your BMW key was stolen (
1)