I doubt that the firmware would be the problem, i have k200d v1.01 and it runs fine with Eneloop NiMh-batteries.
Maybe the problem is physical, alkalines are 1,5V while NiMh-batts are 1,2V. While in storage it is possible that some electrolytecondensator in camera has dried (this could cause the power leaking during night) or contacs had oxidated so combined with the lower voltage of NiMh this makes your camera think batteries are empty. However, K200D is known to be little picky when it comes to NiMh.
Clean the contacts up and try again.
In some cases electronic devices have woken up, even "resurrected" after long storage when they get little powerboost. Maybe using alkalines or even better non-rechargeable 1,5V litiumbatteries for a while gets your camera back in line.
And itīs nice to hear that it works, anyway!