You have a touch pad,? Should be able to hold the float button, then it should stay in float. If it doesn't the touchpad is failing. I think there's a float light. I have one new touchpad left, have to look at it.
Nice, that happen w/ my plow snowdogg hd 75 my truck was off (ignition) it would not move pushing
downward. Leave running + float to relax chain + push down. Plow will mount and dismount on your truck w/ loose chain. Good luck. These sites are HELPFUL for us do it yourselfers W/O Spending $$ .