Bacillus cereus is mostly notable for having a very hardy spore. It loves cycles of reheating (each reheating germinates the previous generation’s spores), followed by long storage at warm temperatures that allows the bacteria to multiply. Improperly handled Chinese food reheated at home of in a restaurant) was the classic venue, because it was often reheated or recooked more than once, or stored warm for use during the day. Limiting yourself to to a single reheating, and ordinary refrigeration should be sufficiently safe. The advice to cook it quickly is very good: “warm” = “incubator”
I believe Bacillus cereus doesn’t have an telltale smell or taste, but I don’t know that for a fact. I do know that “souring” is usually caused by other bacteria, which are mostly not pathogens. They might give you a little diarrhea, though, by temporarily upsetting the balance of bacterial species in your gut. This passes in under a day, often in hours. Drink plenty of fluids.
Bacillus cereus causes food poisoning by two different mechanisms. Both produce nausea and cramps, but they differ in their other symptoms
The quicker acting “emetic” form is what we now call a “food-borne intoxication” - a usually mild, self-limited poisoning from a toxin produced when the bacteria is active and breeding. This toxin is not destroyed by normal reheating or cooking (it is more stable than the starches in the rice; you’d ruin the rice before you rescued it). Since the toxin poisons the stomach first, it causes vomiting 0 to 6 hours after eating.
The slower “diarrheal” form is caused by active bacteria or a large load of spores that germinate in the gut. It isn’t quite an infection, more a self-limiting infestation.
(B. cereus is a fairly normal gut microbe, but any disruption of the gut flora can cause diarrhea, until the gut achieves a new balance) Since it relies on bacterial growth, it usually doesn’t start for 8 to 16 hours, and usually lasts less than 24 hours after onset before the gut achieves a new equilibrium. The diarrhea can range from a small volume to profuse and watery. Drink lots of water.