OK I did my best to brick my MKIII and unforunatelly it worked

I tried not to panic (highly recomended state of mind) so here is what I did to recover from essentially a bad firmware image upload (or bad disc if you will)

First of all I had to do something about the stuck disc. I tried all resets and procedures -- even ones from the official BMW upgrade SI. When all of that failed I took that as a declaration of all out war. Now I had to get down and dirty wit the NAV.

I removed NAV deck from the equipment bay after disconecting the battery.

Set the unit on the work bench and prepared all of the tools needed to open a NAV deck.

Removed the unit cover, removed disc mechanisam (by removing 4 torx screews and carefully detached ribbon cable connecting it to the main board)

Then I located electric load/unload motor wires and its connector then disconected it from the board.

Got the 1.5V battery with short wires attached to it and connected directlly to the motor terminals. The motor started to spin and disc started comming out so naturally I was very happy with that. Note: if disc isnt coming out you have most likelly reversed the the polarity so just try reversing battery wires...

However disc came out only part way. I figured that this will happen as there are other processes that must happen to fully release the disc which I could not simplly replicate.

To overcome this problem I have carrefully pulled disc out by hand and it came out without fuss.

Now this is imortant... at this point you have to insert disc with a known good firmware back in to the unit by pushing it in the possition the stuck one was. You have to do this because deck will think that it still has a disc loaded and will endlessly try to read it. When you do that (do not force disc in just gentle push and if neccessary gently lift the disc clamp enough to pass disc in to possition) then revese battery wires on the loading motor and lover the disc in to the unit.

Reconnect the loading motor to the board put the mechanisam back and reatach ribbon cables.

Now go back to the vehicle reconect the NAV deck and reconnect the battery. Turn the key in the position 2 or start the engine (especially if your battery may die on you) cross your fingers and watch NAV screen come alive with message "loading software" (it may take up to 4 minutes for this to happen) The first clue that this will most likelly work is if the power light on the deck stays on after powering up and of course the messages on the screen. After NAV finishes flash update it will eject the disc and ask you to remove it then press the button to confirm (OK).

After the NAV has rebooted insert your map CD and start the NAV to confirm everything is OK.

Hope this helps as it did resurect my MKIII which got stuck loading bad V31 image (there is a lot of them out there). When things went bad it was ocasionally flashing blank screen and NAV deck would not eject the disc.

NOTE: Anythig you do is at your own risk and there are absolutelly no guaranties it will work. This procedure assumes that your deck is acctually working unit gone bad during software update. This will not help you if the unit is actually defective! If you feel unconfortable with any part of this procedure dont do it!

It is highly recomended to place unit on antistatic mat while on your work surface as well as wearing a anitistatic wrist strap (available at Radio Shack or you local electronics store) or at least take a neccessary precautions to discharge static from your body by touching something grounded such as metal computer case...

I have spent some 20+ years of my life repairing electronics bulk of them CD, DVD & LD drives and static discharge damage happens easy.