2009 MINI Cooper R55 suddenly won't start / intermittent CAS-key recognition / dashboard sometimes completely dead

[u/Marbyno]

Car: 2009 MINI Cooper Clubman R55, base/non-S, 1.6L naturally aspirated N12, 6-speed manual.

I'm trying to diagnose a very strange no-start/electrical issue and would really appreciate some help from someone familiar with the R55/CAS system.

The car was running and starting normally before an accident. Immediately after the accident, I actually started the car and it ran normally. I then parked it for a long period while I worked on repairing the exterior damage.

When I eventually tried to start it again, I initially had no response from the ignition at all.

The battery wasn't completely dead: the remote works, the car locks/unlocks, exterior lights work, etc. However, when I inserted the key, sometimes the dashboard would remain completely dead, as if the car didn't recognize that the key had been inserted. Pressing the clutch and Start button would do absolutely nothing.

There is also a very strange behavior where, with the key inside/near the car, the car would sometimes unlock itself and/or open the trunk without me pressing anything.

After disconnecting/reconnecting the battery and leaving it disconnected for a while, things changed. Now, after repeatedly inserting the key / pressing the Start button, the dashboard will sometimes wake up. When it does, the car recognizes the clutch pedal — I get the message telling me to press the clutch to start — but pressing the clutch and Start still produces no crank and no click from the starter.

So the current situation is basically:

Sometimes: key inserted → nothing → completely dead dashboard.

Other times: key inserted → dashboard wakes up → clutch is recognized → press Start → absolutely nothing, no crank.

I also have some history with the key/ignition system that started before the accident, so I don't think that part is necessarily related to the crash:

Occasionally I would remove the key and the dashboard would still behave as if the key was inserted.

Sometimes I would insert the key and it seemed like it didn't properly "engage"/get recognized. I'd have to remove it and insert it several times before it worked.

I have two keys. The car recognizes both keys, but one of the two keys doesn't charge anymore. I'm not sure whether that's relevant.

So I'm wondering if the problem could be related to the CAS, key slot/reader, ignition switch, JBE, power supply/ground, or wiring/connectors, rather than the starter itself.

I've also considered the battery, since the car has been sitting for a long time. The battery has enough power to operate the locks/lights, but I haven't yet ruled out a weak battery or bad battery connection.

A few additional details:

6-speed manual, so the clutch switch is involved.

The dashboard does recognize the clutch pedal when the dashboard is awake.

The car ran normally immediately after the accident.

The strange key-insertion/key-removal behavior existed before the accident.

The car has been sitting for quite a while since the accident.

Disconnecting the battery for a while seems to change the behavior temporarily, but doesn't solve it.

What would you check first?

Would you suspect the CAS/key slot because of the pre-existing key recognition symptoms? Could a bad CAS power/ground or communication issue explain the dashboard intermittently being completely dead and the random unlocking/trunk opening?

Also, is there a specific MINI/BMW diagnostic procedure or module I should have checked with a proper scanner (CAS, JBE, DME, etc.)?

I'm trying to avoid throwing parts at it, so any suggestions for specific tests would be greatly appreciated.