Intermittent starting issue 125i

[Will_f1]

Hello,
I've got an interesting issue with my E82, 2011 125i (Australian Model) that I'm interested in hearing some feedback, so when my BMW dealer discusses it with me I've got a better understanding of any potential repair issues that could come up.

Recently someone rear-ended me while the car was stopped at the lights (foot on break, handbrake off). A trip to the panel beaters fixed the damage, which appeared small, but at the panel beaters they started encountering an issue whereby the car wouldn't start every time. They did remove the rear bumper for the repair work.

The following symptoms occur (in no particular order)
- Triangle exclamation mark (yellow) indicating the engine will start up next time start/stop button is pressed
- Car on jack (yellow) indicating control of the brake lamps failed, fuel supply malfunction or electrical system of trailer hitch failed.
- System cut's out, all electronics turn off (display and radio) as if I pressed the start/stop button for a second time
- After some tries/retries the car will start and operates fine with all warning cleared and drives no problems.

Trip from BMW road side assist had a look of "no idea" on his face I was told and advised taking it to the dealer, which I've since done and the car is now in for diagnostics.

Car has the comfort access system/keyless entry and start, all operating within reason. Key battery also replaced. Key placed into the holder to start.

Fault from key data at dealer only reports "Junction Box"

Voltage levels on the battery were slightly below standard 12.5 range at 12.2 but when the car had run it went to 12.8 after powering off.

A few things I've considered after some research, but don't completely represent the issue that I'm experiencing:
- The battery is flat
- The terminal to the battery is broken due to the impact (read about some safety feature that disconnects the battery on impact)
- BMW SI B61 08 11
- http://www.1addicts.com/forums/showthread.php?t=707967
- http://www.justanswer.com/bmw/65x0p-...eriencing.html




Has anyone else experienced similar?

[Will_f1]

A call from BMW they said the interfaces to the CAS and PDC that sit within the boot are corroded, water damage...anyone know how water could have got into those areas?

[Will_f1]

Turns out no corrosion, only water damage from exposed rear paneling and the car out in the rain.

Shame good to know BMW's are still a solid car and wasn't directly related to the mechanics of it all.