400D - Strange Battery Problem

I got given this camera to have a look at to see if I could fix it. Here is the problem;

Whenever the main battery is removed and plugged back in, the camera will not turn on at all. As if no power is available what so ever.

The only way to get it to turn back on is to do a hard reset, remove all batteries, CF, lens and wait 20 mins. Plug everything back in and voila, the camera is back working.

As soon as you remove the battery, the camera requires a hard reset again.

Has anybody come across this before, is it a problem with the power board? Thanks.

Have you got another battery to try with the camera.

I would also try reflashing the camera firmware, but you will need to do this with a new fully charged battery, any loss of power during the process will cause problems.

Yes I have two batteries, the original canon and an energizer one. The condition is the same no matter which battery I use.

Just to add if the camera is left for a sustained period of time (ie. overnight) the camera will fail to power up and the hard reset needs to be applied. I have checked the battery and it still has enough power. This concludes that the battery is not being drained whilst the camera is off.

I should be able to upgrade the firmware, as once its on it seems fine. I was taking pictures for around 20 mins yesterday without a problem. Battery still near full charge.

Updated firmware to 1.1.1, still the same problem!!