Replaced the battery in mine with a wal-mart battery. Desoldered the pins and bam, problem fixed for a couple dollars.

You are getting voltage at the battery... is the voltage reaching the board? You can probe before it goes into any resistors to test for continuity of both +3v and -. I did that before replacing the battery to make sure it was indeed the batteries fault. It it passes that test... just send it to that guy for $50. Way easier than probing resistors and other components to see if they failed or if some SMD solder joint has split.

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)