In case you need to urgently access an ATM and you're passing through MB, your problem is solved is right there, just do not panic. Most trains half at MB for at least 8-10 minutes. That time is more than enough, just be quick.
1) Get down.
2) Climb the FOB and come to PF#01 in case your train isn't berthed at PF#01. Take the MAIN EXIT, NOT the FOB exit, NOT the other exit. (The main exit is near the enquiry counter).
3)...
more... Take 10 steps ahead towards the right, you'll bump into three ATMs.
4) Do the transaction.
5) Head back.
All the best.