If we were to encounter alien technology, even if the aliens had only attain a level of technology similar to ours (world wide communication and transportation network with limited space travel,) several factors may make their technology difficult to comprehend.
Alien technology may not be linear
Humans think in a very linear way. Our circuits contain components that connect to other components through linear pathways (wires.) Also, individual components are separated into logical and functional units. Aliens may build circuits that utilize varying areas of intermingling resistance, capacitance and switching. Electricity may swirl around the board instead of follow through separate paths. This kind of circuit would be very difficult for us to understand.
Alien technology may include elements of gravity, nuclear forces, etc
Our electrical technology includes some elements of light and magnetism. Alien technology may include more. If we were to encounter a circuit that use modulated gravity in some way, it would be very difficult for us to figure out. First, we would need to fully understand how all of the circuit components (or areas) transmit data and/or energy. 790
Then we might be able to understand the circuit as a whole.
Alien technology may be multidimensional
Our circuits occupy three dimensions, and many of our circuits can be reduced down to two dimensions. If an alien occupied more (or different) dimensions, it would be virtually impossible for us to figure out (or even full observe) their circuits. We would only be able to theoretically understand them, with help from the designers. We would also have trouble figuring our an alien circuit if the circuit was moving through time differently.
Electricity may behave differently on their planet
There is a strong possibility that electricity may flow differently on an alien planet. They may have stronger, weaker or multiple magnetic poles on their planet. Their sun's radiation may also interfere with electrical signals. In this case, we would have a very difficult time figuring out their circuits, if the circuits were to appear on earth. We probably wouldn't get any help form the aliens either. They would probably have no idea why their circuits stopped working once they arrived on earth. 197