When a cell dies, its biochemy stops for whatever reason, its larger biochemical molecules, DNA (spiral staircase, self reproducing storage of information), Amino-acid-chains ("tools" to transport and build all the stuff), polysacharides (energy transporting chains, "raw materials" made of sugars) and large structural molecules split up into smaller parts without getting renewed by the DNA and amino-acid-chains.
Generally it splits up into many small anorcanic molecules, mostly a lot of whater, methane and other smelly gasses and tasteless fluids.
Chains of at least 100 molecules, full of information and the ability to rebuild others and themself out of smaller molecules, split up into their molecule parts that have way less information.
Were that starts and how it looks like depends on the cause of dead.