Opened up heater it sparkes and lights a pilot but not the burners it tries multiple times but no burners

It sounds a lot like the gas valve could be bad, but you need to test the thermocouple first. There are testers and meters for millivolt testing. You need to find out how many millivolts the thermocouple should put out and then test it, and even if it isn't showing enough voltage it may need only an adjustment to put enough voltage. The flame should be on the 3/8" of the tip of the thermocouple only and no more. Sometimes a gas valve will be good enough to keep the pilot going but the coil for the main gas valve could be bad.