Battery failed, manual key won't unlock door

[dubois]

2013 BMW 120D Xdrive M Sport. F20
Battery completely dead after period out of use. Key from the remote will turn but won't lift button inside driver's door.
Dealer suggests RAC recovery to them, they would probably break a window to get in.
Other suggestions
(1) Jack up, remove undertray, connect battery charger to starter motor feed.
(2) Break into air inlets to access bonnet release.
(1) is difficult due to (very!) old age. (2) uncertain of detailed procedure.
Any other ideas, gents?
Or details of (2), please.

[dubois]

Sorry, Tyre Smoke, if my opening post gave the wrong impression.

The BMW dealer Technician said that key should turn about 45 degrees clockwise (rhd car) and then lift the button. The key easily turns that amount but no further, despite persuasion with pliers. A "deadlock" operation was mentioned but discarded (perhaps rather too quickly) as a possible explanation.

I've tried both keys, both ways up, turning clock & anticlock-wise, with & without lifting door handle, both before & after key operation.

Is it possible that a deadlock system in fact exists and has been triggered in some way by my flat battery?

Not surprisingly, operation of the mechanical key has never been checked (ex demo car). Followers of this post might like to check it works on their car - no need to run your battery down, if you do be sure to leave bonnet open!

There is no evidence that the lock itself is at fault.

Thanks, Simes205 for your suggestion, but I've tried that.

Also thanks, Locknut, I'll try WD40, but lock operates easily.

I might pursue option (1) above - jack up, remove undertray to access starter - with some younger person's assistance.

My Haynes manual (for previous 1 series cars) is locked in the car; can some knowledgeable gent please confirm that my (2013 BMW 120D Xdrive M Sport) starter is readily accessible this way?

I've done virtually everything on my cars for over 60 years, including engine rebuilds and competition preparation, and don't like being beaten. In contrast, no work on BMW save changing headlamp bulbs; servicing at dealer's - 5 year plan supplied with the car.

Finally, is there Manual and/or Parts Catalogue available (online?) for 2013 models?

[dubois]

Thanks very much gents Matt_E_Mulsion, BFleming, helix402 and isleofthorn.

The manual/parts will be invaluable. My charger will deal with the AGM battery safely - 14.8 volts maximum charge if I remember.

I don't subscribe to BMW Emergency Service, but wonder if RAC Homestart might assist with an auto locksmith. Is it really a 10 second job?

The number plate bulb trick will only work (I think) if you ran the battery down by leaving the sidelights switched on.

Thanks again everyone. I'll report back.

[dubois]

Success, with a squirt of WD40 and turning the key with a small adjustable spanner, easier to judge the torque on the key.

After getting a new AGM battery, I shall be turning the key from time to time to check. Suggest this is a GOOD IDEA for everyone, say at Mot time.

Thanks to all who helped.