Mini pin problem

Hi!
I've been troubleshooting an arduino mini which has a strange problem:

I've connected some switches on multiple digital pins with resistors.
While doing a digitalRead and pressing on buttons,
pin 9 and 10 (physically 12 and 13) act as if they're the same:
whenever I press on one of these two, they both trigger.

I thought I had a short somewhere but after lots of tests, I think it might be the mini.
So after puuling it out of the circuit, I tried measuring the resistance between the two pins and I get 60 ohm, which is much lower than any two other digital pins which is approx. 800ohm or more

What could cause that?

hi

not sure what pins your re referring to as there are a few labeling models out there. On the schematic, IO13 is connected directly to a 1K resistor, so if you are getting 60 ohms between 12/13, that means there is a physical short on the board before the resistor. Also, you might want to be aware that making ohmmeter measurements on static sensitive silicon can lead to damage in some cases. Doesn't happen often, but it does happen.

D

Thanks for the info!
I can't figure how a permanent short could happen on the chip by mistake, no solder drop, so maybe a factory defect?

have a good weekend!