in short (and this is in general) a unit/terminal will play as per usual until it triggers a top box feature. if it searches and cannot find the topbox/slave, then it will continue the wins via the reels OR it simply doesnt initialise at all.
Yeah thats normally the case, but on party times in certain circumstances it will cause the machine to think its still connected, hence no comms to master message but will not go up. This has been a known issue, and also as others have said they go off there tits when its put back right.
For obvious reasons im not going to explain the circumstances of how it happens, as it has been exploited on occasion by arcade staff / owners.