Parasitic Battery Drain e53

[HotWheelsRedline]

Hey Guys - I'm new to this forum. Have been on BimmerForums since 2007 for my 1998 M3 e36 vert and my wife's 2005 X5 e53 SAV -- but learned this forum digs deeper into the X5. I've searched for parasitic battery drain threads and found lots of theories (FSU, NAV, TSU, Aux Fan, Radio, gear shift light/sleep mode, etc.)

Our X5 has a parasitic battery drain that started June 5th. Replaced the dead BMW battery (don't know if orig, we're 2nd owner) and alternator tested fine, so thought we were good to go. June 27th, car won't start again -- jumped, runs fine. July 8th, no start -- this time alternator showing drain. Replaced (115K-mile) alternator with new Bosch. July 19th, no battery power again. Thru all of this, never any warning lights on dash.

Re-charged the battery. With multi-meter bridging disconnected neg battery cable/terminal, and all power off, still reads a draw of .40 amps. Pulled/replaced all fuses in glove box and trunk while watching meter for any drop to normal, but nothing.

Now my friend/indy mechanic is checking it. Has ruled out the radio, Aux fan, TCU, FSU, NAV, sleep mode. Today says it may be the electronic trunk latch and is doing further testing. Fortunately, he's not charging me by the hour for diagnostic and gave me a free loaner 325ci.

Can anyone weigh-in with other theories/thoughts? Thanks much.