Batteries and other issues

I have been asked to look at the 4 Segways we use at work. Two are XTs and two are X2s... They have been sitting for about a year and the keys are not labeled. I was able to get two going, one of each model, but the other two show a red light for the front battery, so no go.

I tried removing the front battery from the running one and putting it on the non-running one (same model) so that I could at least know which keys go to which Segway. It's not turning on... I am seeing that the battery indicators are green, but they blink at different rates. Does this mean they are not communicating and therefore I won't be able to turn the Segway on?

Thanks for any help