2005 Jeep Grand Cherokee

Have the battery tested at an auto parts store, especially if it's more than three years old. A simple battery test you can do: When it won't start/turn over, jumper it and see if it runs. If a jumper helps, it would indicate the battery is at fault. Don't rule out the starter yet. They bind up when hot. Don't go to a dealership. An independent mechanic can fix that. Be careful doing jump start if you are not mechanical...get help.

There's no starting issue when outdoor temp is cool. Dash lights turn on when key inserted so I hadn't considered battery. We pulled out starting relay, pulled plastic housing and reinserted into fuse block. When key turned over and relay engaged it did attempt to start (even when hot outside) so we figured power to starter was good.

It doesn't take much power to turn on lights or beep the horn, but a starter can take 500-700 amperes to turn an engine over. A tired, old battery can't do that so testing it for free at an auto parts store might be a good place to start. They can even "load test" the starter to determine it's condition too. They test alternators. The problem is electrical so get it all tested for your future peace of mind.