something is draining the battery. a new battery will last a couple days if just starting the car. even if your alternator is bad.
Check headlights and dashboard lights first. If no/minimal power for the lights then replace battery.
Battery is dead?
I dont have an answer but I am having the same problem. My car wouldn't start but when I turned the key, the lights (hazard and dash lights) started blinking. I think it's a warning that the battery is not completely connected. We tightened the clamps (which were very loose) and it stopped.
check your battery connectins. you could have a bad ground
You probably have a bad ground. Check the grounds on the brake lights.
Have you had the alternator tested? Often a bad internal diode can drain the alternator overnight.
Either the battery has a dead cell, which will normally drain it overnight, or something is on pulling power from the battery. If the battery has a dead cell it will have to be replaced. The easiest way to determine this is to fully charge the battery and then disconnect the negative cable overnight. If the battery is dead in the morning it has a dead cell. You may not even be able to charge it with a dead cell. If the battery is still fully charged the next morning then you have another problem. Check all the lights on the vehicle. Under hood, trunk, dome, curtorsey, glove box, etc. One of them may be staying on. Also check your brake lights. If you find no lights are on then you may have a relay that is sticking. Can be power windows, locks, seat, etc.
Do you mean What does it mean when the brake and battery lights come on in when it is already started? Check your alternator may be its not working well it cause the battery sign comes out.
Assuming it started and ran before you changed the battery, and changing the battery actually is when the problem began, the starter relay wire has been left off and needs to be connected at the battery terminal. I would need more information to diagnose it further.
why would the lights and the horn stay on all the time just started when the battery was changed
Can be a dead cell in the battery. If so the battery will have to be replaced. Can also be any light that is pulling power from the battery. Check all lights. Under hood, glove box, dome light, trunk, etc. Disconnect the negative battery cable overnight and if the battery is dead then the battery has a dead cell and must be replaced.
Check your battery, it may be weak or dead and needs to be replaced.