2000 Chevy Suburban Smoke coming from under hood, engine wi

My wife was driving the Suburban today; she got about a block from home and noticed smoke coming from under the hood. She turned around and drove it back home. The obvioul smell of something burnt under the hood is present. Upon inspection, I could not find any burnt cables. The serpentine belt is still in tact. When I turn the key to start the engine, it will not start as if someone was holding engine and not allowing it to crank. The engine torgues a bit but cannot turn over. It does not click like when the batter is low, so something is holding the engine back. This could be unrelated but something I have noticed, I have noticed a slight coolant smell over the past few months and have had to add a little coolant to the tank maybe once per month.