Showing low battery

I took my camera (Minolta Dimage A1) to Sony in March 2008 to replace CCD chip. After 2 weeks I went to pick up the camera from Sony, put the battery in, it was showing that battery was low. I mentioned to the person behind the desk. She said your battery must be dead. I tried the other battery, still the same. I thought some how both batteries are not good. I did not use the camera till October, I bought 2 new batteries, camera was still showing, batteries not charged, I bought the battery tester (Volt meter) to check the voltage, battery was fully charged. I took the camera back to the Sony and told them that technician must have damage some thing in the camera when tech was replacing CCD chip. Sony refuses to fix it. Sony wants me to pay $225.00 + tax to get it fixed. If any one know what should I do. Please let me know. anjali-white@hotmail.com