Leds work nothing else does

Have an Envirphat which worked fine. My rPi Zero stopped working so got a new one. Just transferred SD card over and updated all software and fresh install of envirophat software.

The leds work fine on the envirophat but everything else returns an I/O error. I2c is definitely enabled. Running i2cdetect finds nothing attached!

Help!

What were the symptoms of the Zero stopping working? Suppose there is a risk it may have overvolted the phat?

That sounds likely actually! The Zero just gets really really hot and no lights go on. Didn’t do more diagnostics than this…

I think my student attached the phat back to front - could this have been the problem?

Sadly yes. Shorts and voltage reg death often result from powered on misplaced hats.