Then, you are going to have fun as the soot will be in every nook and cranny possible..
Totally take apart the system, every piece has to come out and be cleaned.. all contact points, connections, circuits, slots etc.. right from the inside of the cd-rom to the inside of the floppy.. including the power supply..
As soot is carbon-based (unburnt hydro-carbons), it will conduct electricity.. any amount left inside across two points that shouldn't be connected could and probably would result in a burnt out circuit.
I really don't think this is the job for the end-user.. and very possible a tech wouldn't even tackjle it or no guarantee if they did..
Murray