Key will not turn in the ignition after battery change

[Ole]

2 days ago i replaced the battey in my s500, i started the car and everything seemed fine. After twenty seconds the car stopped by itself, after that the key won’t turn and my central locking system no longer works. I can take the key out of the ignition but it won’t turn. Anyone seen something like this before? I have tried disconnecting the battery and I have checked fuses. Any tips?

 

[alexanderfoti]

Check all main fuses in the engine bay, sounds like one of them has popped!

 

[mersum1es]

..check battery leads...

 

[Ole]

Battery leads are ok, I can still use my headlights, ac and radio. I will check all the engine bay fuses again later today. Thank you for the responses

 

[Ole]

Update:
I’ve checked all fuses in the engine bay and under the rear seats just in case. Battery leads are fine with minimal corrosion, I have cleaned them up. Any more ideas on what might be wrong?

 

[Ole]

Found the problem! It was fuse nr.78 hidden behind the right hand side door in the dash, thank you all for the tips

 

[mattkh]

Found the problem! It was fuse nr.78 hidden behind the right hand side door in the dash, thank you all for the tips

Well done.
Had the fuse blown or was it just corroded/come loose..?