How do I test a cryogenic microwave component at room temperature before cooling to millikelvin?

Testing a cryogenic microwave component at room temperature before cooling to millikelvin provides a screening check to verify basic functionality and catch obvious defects before committing to a costly and time-consuming cryogenic cool-down (which takes 24-72 hours for a dilution refrigerator). Room-temperature tests that predict cryogenic performance: S-parameter measurement with a VNA (measure S11, S21 at room temperature; the resonator will have a much broader (lower Q) and shifted frequency at 300K compared to 20 mK because: the superconductor is in the normal state (resistive) at 300K, and the kinetic inductance changes dramatically between normal and superconducting states; however: the room-temperature measurement reveals: open/short circuits (broken wire bonds, bad solder joints, cracked films), approximate resonance frequency (shift predictably by 1-10% when cooled), coupling quality (the external coupling Q_c is determined by capacitor geometry and is relatively temperature-independent)), DC resistance measurement (for superconducting devices: the room-temperature resistance of the superconducting film should match the expected value based on the material's sheet resistance and the pattern geometry; an anomalous resistance indicates: broken or narrowed traces, short circuits, or contamination), optical inspection (microscope inspection of: wire bonds (intact, correct height and placement), film quality (no delamination, cracking, or particulate contamination on the chip surface), and connector interfaces (clean, properly mated SMA or SMP connections)), and continuity and leakage (verify that the coaxial connections are continuous and that there are no shorts between signal and ground).