Not much you can do about the battery if it's dead, other than ordering a replacement.
Software really isn't a problem or issue. If for some strange reason it is, it can be reloaded.
Again, not much you can do about wiring/sensor/electrical problems due to age or internal plastic parts becoming brittle with age and breaking. You can be sure to treat it gently, make sure it doesn't get dropped, fall off an edge, or get stuck under furniture to help keep it from getting damaged. RB's are typically built more solid and aren't as old as other pleos. I would be surprised if you purchased a new pleo RB and it was more than two or three years old at most. The 6+ year old pleos probably aren't RB's and are being bought 2nd hand. the Pleo RB model is just now reaching 6 years old, and it's very unlikely any original stock is left.
You can also start immediately protecting the skin by treating it (there are lot's of discussion threads on what to use or not use, but currently Gibb's is the best recommendation), and by making sure to always return it to the packing position when storing to prevent stretching the skin.
Most untreatable mechanical issues (like dead battery or faulty electrical) should show up within the first few weeks. So you might want to hold off on treating the skin for a few weeks in case you have to return the pleo.
It's also true that you have to remember that people who have RB's that work well, typically don't post about it. The people who post are those who have problems and are looking for help, therefore the majority of material on-line will be about all the problems. There are perfectly good Pleo RB's out there. An if you want to ensure you get one that hasn't been in storage for a long time, you safest bet is to buy directly from PleoWorld of a licensed reseller. Sadly, that is also the most expensive choice.