MyE28.com

Help!

Drove the M5 to work today after getting it registered and after parking here at work I went to roll down the windows-- dead.

So it seems my battery connection has worked it's way loose.

Go to check and the trunk won't open!
Seems like the button/release is disengaged and the button doesn't do anything.

The trunk must be somehow caught on the latch and I can't work it free with the key in the trunk latch...

Any tricks to help it work itself free? Tried pulling the trunk side to side, no dice.

Not sure how to get the car started if it doesn't have a good battery connection!

EDIT:

Saw this post, may have to try it later today if I can't get the trunk open otherwise:

although it does involve drilling a 1/16 inch or so hole.

There is a rectangular black surround piece around the trunk push button lock cylinder. Drill a small hole just at the junction of the top of this surround piece with the sheet metal. Drill parallel to the push button, and exactly above it, in the midline of the car. The drill will penetrate outer sheet metal, then drop through a space, and hit the thicker metal of the lock assembly. Drill through this. The drill bit should penetrate through this a a depth of 2 7/8 inches (measured from the outher surface of the push button. Then just advance the bit (without drilling) another half-inch or so. It will hit the lock's opening mechanism. Give it a small push, and the trunk lid will pop open.

The hole will not be visible unless you kneel down and look for it. It can be sealed with a small dab of silicone, and you can use the hole again if you are ever locked out of the trunk.

So dead that the power locks don’t work as well? Sounds like it’s just locked to me.

I would think if you could just get another battery and some cables, you could hook “+” to the alternator “+”, or starter "+” terminal and ground to one of the good grounds in the engine bay, that should give you lock controls at least.
Keep in mind that I have absolutely NO idea what kind of access you have in the M engine bay. So I apologize if this is a laughable suggestion. Just trying to help.
If you can get a good connection to one of those spots, you should be able to start as well.

Correct.
Drove to work, shut the car off, went to turn it back on and nothing. I'm pretty sure I didn't tighten the battery connection down real well... Battery is fine but I can't get to it now to fix the connection!

Sometimes helps to push down on the trunklid as you push the button. Can you feel the button doing anything? When it's in the locked position there's nothing on the other side but when it unlocked the plunger is contacting something and you should feel that.

Another thought is to backfeed the electrical system by hooking a set of jumper cables to a good ground and the main post on the starter. That's where the positive cable from the trunk lands. This would at least enable you to cycle the power locks. Perhaps even start the car however if your battery connection is truly kaput I'm not sure how safe it is to try this. The car will want a connected battery when running.

Tried pushing down in the middle and it didn't seem to help. Wiggled the trunk from side to side, pushed the bottom lip towards the front of the car etc.

Pushing the button, I don't hear the typical engaging of the latch mechanism. At the very end of travel I hear something. Turning the key in it and it feels 'empty'.

I had this happen on my E24 and it turned out the upper latch had become loose was catching in such a way that you couldn't get it free (eventually I did).

Wouldn't be as big of a deal if I could at least start it up and drive it home for the weekend.

You can definitely get it started, I'm just not sure what will happen when you disconnect the jumper cables if your battery is truly disconnected. And this could be bad for the car! Just by hooking up a battery and cycling the locks you may be able to get the trunk lock to jiggle free if that's what's hanging it up.

You can power up the fuse panel with a battery or a jump box and unlock the car.

So if I understand you can't open the trunk with the key? I think the lock must be in the horizontal position to engage.

The car was and is fully unlocked. The trunk is simply caught on something and will not open with the button (and key in the button).

It doesn't seem like it is completely closed and latched, rather partially open but will not pop open.

Hence I can't get in the trunk to get to the battery. No need to cycle the locks as I don't think that is the problem. Turning the key either direction would not lock the car from the trunk last night (that's when I originally realized the problem).


EDIT, Was able to get it open by pulling the trunk hard to the left. Seems like the latch/lock mechanism had shifted slightly to the left and the lock shaft had popped out of the holder (so power locks would not work anyway). Pushing the button didn't engage the release since it was at an off angle to the cam that pushes inward.

Got the battery connected and secure.

Need to get proper alignment tonight to make sure the mechanism doesn't shift at all next time!

You can jump the car carefully from under the hood, though you may just wish to try cycling the locks with power applied just to see if you can get it to unlatch. To jump from under the hood you have to go straight for the starter wire for your positive connection.

Edit, nice work!