I recently purchased several of the DFRobot ledkeypad shields: https://www.dfrobot.com/product-1407.html
I have Arduino Leonardo (which also had some problems in the beginning, being recognized as modems). My OS is Linux Mint, and I'm using the last Arduino IDE.
The library I use is the one recommended on the website of the vendor, LedKeypad.h, and works fine with the other shields of the same model from the same batch.
Some shields worked fine but I am now having trouble with one of them, which seems unresponsive. I can load for instance the blink program in the arduino, and it works, but the shield does not work. When it is plugged in, the fours dots are slightly red, and I cannot turn them off.
I tried displaying something on the serial monitor when the buttons are pushed, and only one of the 5 buttons works (the KEY_DOWN one).
Is there anything I can attempt to fix the problem ? Or should I just give up on this shield ?