If it was brand new, then I presume that you've removed an old battery that had been in there since manufacture?
That being the case, you may want to VERY carefully use a small, flat-head screwdriver to slowly and carefully slightly bend the battery contacts upwards/outwards. The old battery is likely to have flattened them over that amount of time, causing a bad connection. Again, be careful - you don't want to break anything.
I can't comment on the reset button, unfortunately, but the above is what I would do to address a bad connection in a brand new device that was released a long time ago.