Just bought 2 RCA Voyager III tablets for my Grandsons for Christmas. One the 1 it looks like something exploded inside the t

If they are new and not working, return them and have them give you functioning devices. No new device should give you problems.
 
Solution
That seems rather odd. Unless you don't have a receipt, or are past the return date. They will usually allow for exchanges longer than returns. However if it has been a while (say month or more) then you should contact the manufacturer.