Try this. Remove the spark plug, and place a large rag in front of the spark plug hole. Ground the spark plug wire. Turn the engine over, try to start the engine. I'm guessing that the cylinder is filled with a gas oil mixture. You will see gas fill the rag. You ground the plug so there is no chance of a spark, as you are going to get a lot of fumes. After no more gas comes flying out, install the plug and change the oil. Then try starting the engine.
NO, I DON'T THINK THERE IS ANYTHING WRONG WITH YOUR STARTER OR SOLENOID OR ANY OTHER PART OF THE ELECTRICAL SYSTEM. THAT'S WHY I MADE THE RECOMMENDATION FLUSH THE CYLINDER FIRST.
Hope you find someone who is smarter than me to help you, because I'm out of hthis one.