I happen to have the exact same chinese aliex tester. I don't know much about Arduinos and stuff, so I wanted to find an instruction how to change the firmware. Because I can't even recalibrate the capacitance settings... Well, you probably have the same firmware, so you know. Right, so I don't know much about programming, but I can use a continuity tester. And here's what's strange. Everything you said checks out. So the 1st hole goes to 18th pin, the second - to the 21st pin, the reset (why no pin number? it's 29 on mine) - and so on. BUT
when I check it, it shows me the voltage drop, the usual 0.6v (0.57v to be precise with inverted voltage, so black probe on a pin) and 1,087v the other way around (black probe on the ground), so I think your chip is cooked or you forgot to disconnect something. Just to be sure I checked it on my Arduino and it shows very similar numbers