With a touch, you place an illusion on a willing creature or an object that isn’t being worn or carried. A creature gains the Mask effect below, and an object gains the False Aura effect below. The effect lasts for the duration. If you cast the spell on the same target every day for 30 days, the illusion lasts until dispelled.
Mask (Creature). Choose a creature type other than the target’s actual type. Spells and other magical effects treat the target as if it were a creature of the chosen type.
False Aura (Object). You change the way the target appears to spells and magical effects that detect magical auras, such as Detect Magic. You can make a nonmagical object appear magical, make a magic item appear nonmagical, or change the object’s aura so that it appears to belong to a school of magic you choose.
* - (a small square of silk)
According to the RAW here, no, though sentient objects are pretty rare.
Let's say there's a magical item that has charges that can be used with a magical action, and it's under the effect of that spell and appears to be a non-magical item.
Can a character (especially a spellcaster) holding that item use the charges of that item if they think it's a non-magical item?
Can they understand/feel that the item has magical charges just by holding it?
Should the DM tell the character that they can use some magical action while holding that item (without other details)?
To answer these questions in order:
Keep in mind, though that all this spell does when used in that manner is prevent spells and magical effects from identifying the object as magical. It doesn't stop someone from telling you the item is magical, attuning to it, or using it once you know what it is.
No, because when a creature dies it stops being a Creature and the body becomes an Object
Dead creatures are still creatures.