Would you blanket this horse in the winter?
Covering the hose will not rid of the smell. Take hose out, cover opening and pack hose to put back later or give to LL.
Sweating is best answer, but be careful not to catch surrounding on fire. Instead of compression, look into sharkbite(push on fittings). They can be found at Home Depot and maybe Lowes, etc. They just push on and are great in a pinch. Compression ftgs will work if put on properly, but can leak if tightened to much or not enough. So if you can't solder, or hire it done, i would look into the push ftgs.
Without SOME description of how you wired the unit, it is difficult to be certain. My best GUESS is that you have at least one wire connected to the wrong terminal. May such alarms have 3 wires. One 'hot', one 'neutral', and one that ties to other alarms so that if one is triggered, they all sound.
If it smells, it needs to be removed. It's got mold or a dead animal in it.