Over the years, my microhood has developed a greasy buildup in the inlet vent screens on the underside of the microhood. They're an aluminum mesh that comes out easily with a label near it saying not to use harsh chemicals or excessive water. The verbiage stops short of recommending the best way to clean them.
I ended up using degreaser and it worked better than I thought.
First, remove the vent screens. In a sink, I sprayed liberal amounts of degreaser on both sides and let sit for a couple minutes. Spray down with water and repeat cleaning if necessary. Dry on a towel. Afterwards, they looked like new.
I guess sometimes the simplest approach is best; don't overthink the situation.
The best thing would be to look in the manufacturer's instructions which may be online if you don't have it handy.
I don't understand what "excessive water" means other than that it may hold a little water if it's not thoroughly dry and if you try to operate it some will be pulled into the fan which wouldn't be good.
I would take it outside and wash it thoroughly in a pan or bucket of very hot water using some liquid dish detergent (Dawn, for example). Then thoroughly rinse it. Shake as much water out as you can and allow it to dry in the sun for a few hours. Check it carefully before re-installing.
I used to try and clean my kitchen vent hood and filters with 409 which was a real drudgery and a huge mess. Since, I have discovered the really easy way! There is a product that comes in a box like powdered laundry detergent called "White King Ultra Water Softener & Detergent Booster." I use a bucket large enough to place the filters into, that has about 1 cup (or more) of the White King and very hot water. Literally, within a minute the nasty, greasy goo just rolls off using a very soft brush on both sides. Rinse the filters in clean hot water. You can use a clean bucket of water and White King to wipe down the rest of the hood. I think the White King may be hard to find anymore, and a relative suggested that any of the dishwasher soaps should do the same thing since they're meant to alleviate hard water spots...just be liberal with the soap.