Help.. Gem BDI problem?

I am a newbie here, looking for some help from a few Guru’s.
I have an early Gem (1996 and 48V)
Anyhow, I changed batteries, due to them being in need of.
I get the new ones installed and when i flip the the key, the BDI is flashing red and yellow. I check the voltage to controller showing 48v. I then check voltage to BDI showing 48v… So ireplace the BDI thinking its toast.
I install the new one and it instantly shows full charge all bars green.
I pat myself on the back and say to myself im a genius…LOL

I put on charger overnight becuase i ended up using it half the day. The next morning i walk into my garage and the charger shows full charge. I flip the key and the new BDI is now flashing the same way the old one was ???
Please help !! :confused: