Please don't bother.
Meat spending any significant amount of time in the danger zone of 40 F - 140 F (4.4 C - 60 C) that has not been fully cooked should never be re-chilled to be served later. Given that Salmonella can be found throughout poultry, not just on the surface, and that it's almost guaranteed that your poultry had some level of a pathogen present, you shouldn't risk it.
Your not so thorough cooking, likely to an internal temperature of 120 F - 130 F, has basically heat-shocked the bacteria present imbuing them with a much higher than usual heat resistance. On top of that it likely took at least a few hours to get the meat back below 40 F (at which they can still grow, albeit slowly), so depending on the initial amount of infection and the time spent in the danger zone you likely have a bacteria population minimally in the hundreds of millions, possibly in the billions.
In this answer of mine I give a lot of detail regarding the relation between temperature and duration and it's effect on Salmonella. The important take-away is that with any reasonable temperature death is not instant, it's merely a percentage of the population that is killed at any given temperature and duration. As few as 100,000 Salmonella cells can get you sick, and it takes much fewer for E. Coli. So even if you're killing five-9's worth of bacteria, is it really worth it?
I'm all for eating rare meat (not poultry), but only if I'm confident in the quality and handling of said meat before it reaches my plate. Think of it this way, if the meat were exposed to these conditions before it reached your plate it would be considered gross negligence, and would likely result in a recall.
The guidelines that many agencies publish to safely cook meat all assume typical levels of contamination, given proper handling (though they do err greatly on the side of safety). They simply aren't accurate when you are starting with meat that has a population large enough to sicken or kill a small village.
I'm not even going to begin to address the toxic waste products produced by some pathogens, which are not destroyed by heat.
Throw it out and prevent this in the future by being sure to cook it all the way through. It sounds like you likely just grabbed the chicken out of the refrigerator and threw it directly on the heat, this can lead to the exterior cooking too quickly before the interior has time to cook. Get in the habit of setting your meats out for 30m to an hour so that it reaches room temperature throughout, but cook it immediately, do not re-chill it.
I'll assume that you're talking about pure maple syrup in a glass container; if it's that adulterated pancake syrup then it's probably riddled with preservatives, so any advice here doesn't apply.
Pure maple syrup can and will grow mold on the surface if left in a cupboard. There are several reports of this happening, and although several of those people say that it's OK to simply strain the mold and re-boil the maple syrup, (a) I wouldn't chance it, and (b) that process is hardly any more convenient than simply taking it out of the refrigerator a half-hour earlier and letting it come up to room temperature.
Maple syrup should be stored in the refrigerator. It doesn't have to be, and it will probably take at least a year for it to grow any mold if left in the pantry. But it will last longer in the refrigerator; I've seen refrigerated jars 3+ years old without any mold.
Best Answer
Fist, what do you mean by "proper?" If your chicken was correctly cooked, then chilled to refrigeration temperatures within the window for food safety, and stored within the window of safety, you can obviously eat it directly from the refrigerator...or warm it and eat it. No significant bacteria are going to grow, for example, if you remove it from the fridge, stick it in the microwave (or in pan on a stove) and warm it for a few minutes, and eat it. There is just not enough time for anything to incubate. Again, the preceding assumes that you've followed general food safety protocols for your raw product, preparation, cooking, and storage...and you are consuming within the storage life of your food.
Now, if you've got some time, and your goal is to reheat to have an experience as close to the original cooking as possible, the then best tool is to use a sous vide device. It is the most gentle and thorough tool for this job. This is a good explanation. All you have to do is set the device to a degree or two under the original doneness temperature, bag it, and put it in the bath. It's the path toward moist leftover chicken...among other things.