@Frederick If you’re using SDR#, you should be able to see the waterfall and the spectrum in real time (live), so you should get an idea of whether your system is picking up any signals from the satellite(s).
You can check if the system is deaf by tuning to e.g. FM stations and see if you’re picking any signals up (i.e. debug if the signal travels through the antenna, LNA and SDR as it should). To check if the LNA works, you can plug it in/out of the antenna (an LNA should generally be placed immediately after the antenna). If the overall noise increases, then the LNA is working, as it is indeed amplifying input signals and internal noise that it unintentionally produces.
In SDR#, I would make sure to click the Gear button at the top left corner and ensure the options “Offset Tuning”, “RTL AGC” and “Tuner AGC” are all unchecked, and “Frequency correction (ppm)” is set to 0, like so:
Your RF gain should not be set to 0 dB (otherwise the RTL would be pretty deaf), but it should not be maximized either (e.g. to avoid over-saturation/clipping by the ADC (if your environment is RFI-rich)). Ideally, you should start from RF Gain = 0, and slowly increase the gain until you see that the signal-to-noise ratio (S/N) in the live spectrum maximizes. At some point, increasing the RF Gain will no longer improve the S/N. Usually for an RTL, the nominal gain should be around 8 dB, but I think it’s safer for you to set it to 12 dB to ensure the RTL will pick the signal up.