Vans not starting

My battery died a week and a half ago , I got a new battery and changed it today, as I
was finishing up the van started on its own,(keys in my pocket) I tried putting the key in
the ignition and turning it off and nothing, then I applied the brake and it shut off and lost
all power again. The van does have a remote starter but that has never worked in the year
Ive owned it. Anyone have a suggestion as to what may be wrong ? Thanks