the water will never reach the lid if the pump works. water gushing out from under the lid is a sign that your pump is not working. another sign is that the water comes out when you flush the toilet because the tank is full because the pump is not working. also if the drain line is clogged, but that's highly unlikely. if your tank has an alarm it should have gone off if the tank was full. you can test the pump to see if its working, if it just hums when you turn it on it may be jammed if someone uses toilet wipes in your house those might jam the pump depending on the pump.