New battery still won't start

2001 Mustang, replaced the battery but it still won’t start. tries to turnover but won’t. Electrical or fuel issue?

Does the engine CRANK (turn over) at normal speed?? Miles on car??

With a new battery the engine should be turning over fast and strong. If it’s not then it sounds like an electrical problem.

Only if the new battery was fully charged.

They generally are. I’d check the ground wire. Might be chewed through or making poor contact.

What did you replace the battery with?

If the engine “tried” to turn over with a new and fully charged battery ,but would not turn over, then the issue has to do with the ignition system. You might have a bad starter, or loose battery or starter connections.