My 97 camry starts in the acc on position but will not crank if I try

I have a 97 Camry its an automatic v6 it recently broke down after it Was running fine went into the store bought groceries came out acted like the battery was dead car wouldn't attempt to crank. Tried jumping it nothing happened. 5 days later I went with car trailer to pick it up put the key in turned the ignition to on. Position and it started but starter wont disengage now. I put a new starter in it still same problem all wire connections are tight battery terminals are tight totally clueless on what it could be