found this forum and have had some of the same issues.

Been having a nightmare for over 4 months now and need some advice.  I know very little about cars but i just cannot wrap my head around how the dealership is unable to get my Range rover working. long story about what all has happened over the past 4 months, sorry if its a little jumbled.

In July we brought our 2008 Range Rover HSE into the dealership because the AC was not blowing out cold air.  We were told we would need a new compressor ($2100 for parts and labor).  We went ahead and did that and also had some airbags replaced that were recalled.  Got our car back a week later an everything seemed to be working great.

4 days later while we were driving, the radio started shutting down and rebooting itself every few minutes.  When we finally got to where we were going and shut the car off, the dashboard read "key in ignition" but I had removed it and was in my hand.  The dashboard was also showing "terrain warning." When I tried to put the key back in, the car would not start.  Would not turn over at all but the electronics and light would still come on.  

When we got the car towed to the Range rover dealership, we were told that this was only happening because the new compressor that was installed was sucking too much juice from the battery and we needed a new/larger battery ($500).  The new battery was installed but did not solve the issue.  
While our car was at the dealership and they were trying to figure out what was going on, the suspension sensor went out. We were told that that could not do anymore testing on our vehicle until this sensor was replaced ($1800).  Again, this issue happened while the car was in their position and they were driving it.  We were also told that they couldn't release the car to us like it was so if we didn't want to replace the sensor then we would need to come with a flatbed and have it towed away.

We pay for the sensor to be replaced and moved on. Got a call the following week saying our Range Rover was ready to be picked up. Went the next day to go get it and wad handed a key that the cover was ripped apart.  They tried telling us that it came in like that (100% did not).  it also would not unlock any of the doors, it would only start the car.  I got the manager to agree to replace the key but I was still going to have to pay several hundred dollars so they could program the new key.

As soon as we pulled out of the dealership, the same issues we originally brought it in for (electronics rebooting/terrain warning) started happening again. Turned right around and dropped it back off. Our Range Rover a now been at the dealership for over 3 months and it seems like they are just doing a trial and error approach to see what is going on because they cannot get the car to start normally.  So far we have replaced the ignition switch, anti theft module, instrument cluster, and the audio control module.

They keep telling us that there is a short somewhere that is bringing the can bus down, but have not been able to find where the short is.  They also keep assuring me that this was not caused by any of the work they did when the new compressor and airbags were installed.

Does anyone have any idea of what is going on or what we should do.  I have already considered just lighting it on fire but have sunk too much money into it already in the past 4 months.  

Firstly welcome to the forum. I can't offer much in the way of your problems but if I were in your shoes I would run a mile from the dealer you are using. . They are surely ripping you off.

Do you not have a decent independent in your area? John
2008 Stornoway Grey 3.6 Tdv8 Vogue
2005 TD6 Java Black Vogue - Written off!!
GAP iiD BT
2003 Discovery TD5 Auto, Nanocom Evolution - gone to a new home!
MasseyFerguson 152 - No electronics!! - Sold

For a CANBUS error I would not replace any module unless unplugging it removes the fault condition. If no module on that CANBUS is causing the fault then the wiring is faulty, presumably with a short circuit because an open circuit wont shut down the CANBUS, only isolate some modules. A CANBUS wire may have to be temporarily cut to isolate the front and rear parts of the wiring to determine if the short is forward or behind the cut, then rejoined and another cut further forwards or rearwards to eventually track down the defective wiring. A multi-meter can be used to check resistance at the site of the cut to determine on which side of the cut the short circuit is located, so the vehicle doesn't have to be started or even switched on. An initial check at the diagnostic connector would confirm a short to ground or a short between the 2 CANBUS wires before starting any unplugging. A wiring schematic would be necessary.

The MY11 wiring schematic shows 2 pairs of connectors where sections of the MS canbus is isolated if unplugged and 1 pair that isolates sections of the HS canbus but earlier models may be different.