Husqvarna lawn tractor won't crank

My battery is 2 years old. I took and had it checked. it is fully charged. I changed the spark plug and the gas filter.  the light on the tractor blinks green but when I turn the key it turns red. I don't hear any sound most of the time when I try to crank. once in a while it will act like it is getting signal. is this a bad ignition module? i was riding it the other day and went to turn the key to put in reverse and key came out . My tractor requires you to turn the key back to go in reverse.  it stayed cranked. I have had issues for several months getting the key to go all the way in. I had a spare new key and i got it all the way down one time today.