What does it mean when red flashing key symbol in dashboard and car wont start up?

Without knowing your exact brand of car, this is a difficult question to answer. The first thought I have would be that your vehicle has an immobilizer, in which case you will need to take the immobilizer off before you can start the vehicle. If it's not the case that you have an immobilizer on your vehicle, I would suggest you refer to the owner's manual for your car, or contact a dealership.