If the fasteners that attach your Segway Lithium battery packs don't look like the one on the left, then replace them immediately.
Regular checks are particularly important if you regularly use your Segway PT near salt water, or in other wet and damp conditions where the underside of the PT does not get regular opportunity to dry. If corrosion gets in, the fasteners can seize and become very difficult or impossible to remove. Removing seized fasteners can require tools that may seriously damage the battery pack and/or the PowerBase (i.e. the Segway platform).
Each battery fastener has a small rubber O-ring around the underside of the head of the cap-screw. This O-ring ensures a water-tight seal that prevents moisture ingress and subsequent corrosion of the threaded shaft.
Visually inspect the O-ring to ensure it is not damaged. If it is, replace the fastener (do not re-use it).
If the O-ring becomes damaged or if the fastener is not tightened to the correct torque then moisture can leak up into the thread, causing corrosion and seizing. Leaking can occur if the fastener is under-tightened. The O-ring can be damaged by over-tightening.
The correct torque to tighten the fastener to is 1.6 N-m.
Replacement battery fasteners are available from Segway New Zealand, and come with thread-lock compound pre-applied. This is a circumstance where any old bolt will not do the trick.
Here are instructions for the correct procedure for attaching the battery packs to your Segway PT.