This is what you need to do. You need to do a "voltage drop test" This is done while you are trying to crank the starter. I tell people to do this on their electrical problems and they "never" come back saying they tried it. This how an automotive electrical shop or good mechanic finds these problems. It's fast and easy.
The electricity is "exactly like water in a pipe. Voltage is the pressure and amperage is the amount of flow. If you had a blockage in your water system, you would have high pressure (voltage) above the blockage and zero or low pressure after the blockage. We can check for that blockage with a voltmeter. If you put the meters leads on both sides of the blockage while cranking the voltage will look for a way around the blockage through the meter. A zero volt reading would mean there is no blockage a voltage reading more than .2 of a volt means there is a blockage. You start at the battery, put one probe on the center battery post and one on the cable and try to crank the engine. If you saw 4 volts you would know you have a bad connection at the battery post, Then you move the probes to each end of the battery cable and crank the engine. If you see 2V you have resistance in the cable. You keep doing this across every cable, connection and device until you find the resistance. Just because you have new parts doesn't mean they are good. Ever see the manufacturer forget to strip the insulation off a battery cable before they crimped on the end. I worked with a Ford dealer mechanic that had that happen on a new car and nobody could figure out why it started sometimes and other times it did not. A voltage drop test across that new cable found the problem. Watch this video and others. This is how your going to find your problem without guessing.
https://www.youtube.com/watch?v=WMXENKujYtc