Yes, it can ruin a battery and it can explode.
somtimes usually not
Something is causing a drain on the battery even with the vehicle off and nothing turned on. A good mechanic can do a drain test on the battery to see what may be draining the charge. A dead cell in the battery itself will also cause the battery to go dead. Disconnect the negative battery cable overnight and if the battery is dead the next morning it has a dead cell and must be replaced. If not look for a light that is on or a relay that is stuck.
Either the switch was left in the wrong position, or the thing is defective. The dome lights draw enough current to drain the battery overnight.
Does it turn over? Does it have spark? Fuel?
On mine it had a bad carbarator and water in its spark plug.
No,car will not run rich.Infact it gives misfires since escaping fuel will be the ultimate result if we use wrong spark plugs.
wrong spark plug wire configuration. Check to see if two are backwards.
Wrong air/fuel ratio Poor atomisation of fuel Poor spark Incorrect timing of spark
Out of time, or spark plug wires installed on wrong plug.
yes it might cause the battery to leak and most probably explode.
Wrong gap, wrong plug, poor groound when you are looking at the spark,