Please add more sections!
Pleo will 'go to sleep' when the battery runs down, but sometimes the battery isn't getting recharged and Pleo will never wake up, or act very strangely. Make sure the battery is seated in the charger properly. Make sure the batteries get a whole cycle which takes longer than 1 hour, if it's too short, then the battery may be dying, try reseating it repeatedly until charging time is more normal. InmemoryofRomeo has a long discussion of various battery issues.
Neck and TailEdit
Pleo Classic has a long history of issues with neck and tail cables breaking. Basically if the Pleo's neck or tail stops moving in that direction, chances are good the cable on that side broke and you need to move to the repair information.
It's sometimes hard to tell if it's broken or just an extreme behavior within normal operations. Pleo rb has a much wider set of behavior oddities than the older Pleo Classic. Read the manual carefully. Using one of the diagnostic tools to determine the personality state can help tease apart the issue and give you addition information.