I suspected a TVS at the input of a circuit of mine that had problems and when testing with the multimeter I found high resistance in both directions. Is the component burned or good? Is the proof correct, since the TVS are diodes?
TVS (Transient Voltage Supressors) are nothing more than diodes. These diodes, however, appear in several configurations, for example, alone, connected in opposition or in "arrays" as the figure below.
If they are alone, the test can be like a common diode: low resistance in the forward direction and high in the reverse direction. These isolated diodes are used in direct current circuits.
In alternating current circuits, it is more common for them to be connected in opposition two by two, as shown in figure 2.
In this case, we will have a high resistance in both directions if it is in good condition. See, however, that this also does not say whether it is open or even if the chip is "active". One can have an additional idea with the measurement of capacitance, of the order of a few pf that will indicate that the chip is there.