There is a test utility, you may try gpiotest
Here’s what to do, first unmount the Pisound and keep all the pins unconnected, then:
sudo apt install pigpiod
sudo systemctl start pigpiod
sudo systemctl status pigpiod
# It the status command above says it failed, you may have to increase GPU memory
# I had to do it... In that case do:
# sudo raspi-config
# Go to Advanced Options -> Memory Split -> Enter 64, OK, reboot,
# run start command again
wget http://abyz.me.uk/rpi/pigpio/code/gpiotest.zip
unzip gpiotest.zip
./gpiotest
It should write:
Testing...
Skipped non-user gpios: 0 1 28 29 30 31
Tested user gpios: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Failed user gpios: None
on a fully working Pi.
Previously I had success with this script with correctly identifying the pins that were damaged on one of our Pi’s.