also check battery connections are nice and tight after changing the battery.
Also try disconecting it for a while.
did you try charging the battery with it still connected in the car and / or jump start? its possible the former could have sent the elctrics haywire, they may be resetable by leaving the battery disconnected for 10 mins.
other than that, sounds like the voltage is too low on the battery(s) you're trying to use. Or maybe you have a short circuit somewhere?