I originally thought I had an ecm issue but not entirely sure now...
I have been searching forums etc for months regarding my ecm issues. I have read about the recalls and all of the issues. I bought this quad about 3 yrs ago, the seller told me he had some over charging issues and had the exam replaced to the newer silver finned 4011568 module. I drove it on to the truck
brought it home and unloaded it, my son drove it around the field a few times maybe a total of an hour.
We put it away and then it sat for about a year and a half, I was diagnosed with Cancer and was dealing with that and had no time for the quad. My son and other relatives did take it out in the summer of 2016 to see if it would start, it did not. So a new battery was purchased and installed, they managed to get it to start but then it did some weird things, like the fan running after shut off etc. They looked at the area where the ecm is located and saw that the plug had been zip tied onto the ecm, thinking that was odd they undid the zip ties. They checked the plug and it smelled burnt and they plugged it back in and it wouldn't start. It was then put away. In an outdoor storage area. Unfortunately it ended up out in the elaments through the winter.
Finally got it into my garage this fall/winter. Got a new battery, took the ecm out....opened it up...it had gotten water inside it and was all rusted. I took it all apart and cleaned off everything it was like new. I checked the plug now and cleaned it all up and although it was not perfect I thought it would work enough to try starting it. I also changed the solenoid because it was very corroded and cleaned up all the connections for the cables ( battery, starter, solenoid etc ). We used a tester and made sure there was power going from the battery all the way to the winch. All seemed like it should be good to go. I turned the key and nothing, the cluster didn't light up or anything.
So, I decided to disconnect the battery and I used one of those small booster packs and clamped it directly to the wires and tried again...perfect! The cluster lit up, the lights work everything was turning over...excellent.

Here is the problem now, I disconnected the booster pack, hooked the battery back up and tried the key.
Nothing works. This is a brand new battery Showing 12.8 volts. Confused, so I disconnect the battery again...I take a car battery I have that shows 12.6volts and I use booster cables form the battery to the wires on the ATV
I turn the key and Nothing. So I disconnect that and go back and try this little pocket booster pack with 450 cca
connected to the wires...and the key turns and everything comes on and it turns right over.
The only thing I am changing is the power source.

I am am hoping that I was clear with my story and that somebody can read this and offer a suggestion.

i can't really afford to just buy a new ecm for $500 ( I'm in Ontario Canada ) to try it. I do plan to buy a new plug and fix and replace all the pins etc.
It doesn't make sense to me that the ecm still faulty if it will start with a booster pack.

If the ecm is the problem...
I am hoping there is somebody with more experience and knowledge about these ecm modules that could explain to me why the ecm would not allow it to start with a battery but it would start with a booster pack.

Any other answer, solutions or information would be greatly appreciated.
If somebody could explain to me why it is the ecm and convince me that is the problem
I will save my pennies and buy one. But I certainly don't want to buy one if that isn't the issue.

This is the first time I have ever posted on a forum...not really sure how it works.
if somebody has info feel free to email me direct at sbrannigan@hotmail.ca
Otherwise I guess I will just have to keep coming back to this site watching for a response.

Thank you all so very much for taking the time to read my long winded story/issue.