Final answer:
The best first step in troubleshooting a non-working newly installed hardware device after driver and software installation is to check the device connections for any loose or improper connections.
Step-by-step explanation:
If you have installed a new hardware device, upgraded the driver, and installed the custom software, but the device is not working, the BEST troubleshooting step to try first is to check the device connections. This step is quick, simple, and often resolves issues when hardware devices are not recognized or malfunctioning. Loose or improperly connected cables are common culprits. If the connections are secure and the issue persists, then it would be prudent to restart the computer. If restarting does not resolve the problem, proceeding with uninstalling and reinstalling the device driver would be a reasonable next step before eventually seeking technical support if all else fails.