MIC+ V2 only sound on the left speaker, problems with display


I am using the MIC+ V2 with a Raspberry 3B+. For testing purposes I use the test script (wget -O - test.raspiaudio.com | bash). I managed to get the sound card working, the test script worked, I heard sound (front left, front right). I then configured the config.txt file according to the documentation of the display (Waveshare 3.5 SPI display) - which was working before without the sound shield. After reboot, both devices worked. I rebooted again - without chaning anything, the display did not initialize anymore. After that I unplugged it and removed the configuration from config.txt. After that the sound card only plays “front left”, not “front right” anymore. Moving the shield a little bit, it seems that there is a loose contact somewhere.

I will return the device and swap it, but the question: can I simply attach the SPI display onto the MIC+ V2? Does this work - it seemed to be working only one time!