As far as I know from 4070, it is there a verry well known issue of the battery cover the cover is not pressed stong against the battery so it looses contact also the battery on many 4070 is not locked verry strong at the Chassis on 4075 it is a different mechanism and I do not have much experiece on 4075
We got new battery covers from AVAYA to fix the Problem, because it is verry well known by AVAYA