most likely you crossed a wire and caused the same effect as "hot wiring" the car. re check your connection and also every time you install or service an electrical component your negative battery conector should be unplug to prevent just that.
Had the same problem, changed the positive and negative battery cable heads, this stopped the drain. Check and see if the cables are good first.
check your positive on your battery. verify if no power is coming from the battery OR from the ignition. hard to answer without knowing if the problem is coming from battery or ignition. look for burnt wires going to the solenoid. hope you get a more precise answer. good luck. it could be worse!
Ignition switch may be defective.
you have to put the key in ignition, and turn the key to on and lock for ten times. this will reset the computer only . unhooking the positive from battery will do nothing with lights on dash if problem, wasn't repaired.
Check your ignition fuse,its in the fuse box,also,your fusible link could be burnt or melted,its connected to your positive battery cable,if burnt or melted,then its your problem.
Discharged battery Bad wiring connection, positive or negative Immobiliser fault Faulty ignition switch.
the ignition control module could be the problem
If your 2000 Mercury Sable clicks once when you turn the key but doesn't start, it may indicate a problem with the battery, starter, or connections. First, check the battery voltage and connections for corrosion or looseness. If the battery is fine, the issue could be the starter motor or a faulty ignition switch. It's advisable to have a mechanic diagnose the problem to accurately identify the cause.
Transmission Problem Battery Problem Ignition Problem
battery may not be the problem check your starter motor and ignition switch
Something is on, as in headlights or ignition, or the battery has a dead cell. If the battery is over 2 years old it is more than likely the battery itself that is the problem. Disconnect the battery positive cable and fully charge the battery. Let it sit overnight and if it goes dead, replace the battery. If not, find out what is running it down.
Battery, battery cable or connections, starter problem, ignition switch not working. Be more specific please.