Did you accidentally swap pos for neg when connecting back up?
My controller started doing exactly that after making that mistake. It only took a momentary touch and that was it. It was under a year old so I was a bit miffed to say the least, especially when they wanted £40 plus postage to fix it. Dunno why, when they charge what they do for these controllers, that they aren't reverse polarity protected.
I didn't pay to have it fixed by the way. I went back to an old PWM controller. Ten years old and no issues yet.