Wired M5Stack's CO2L Unit (SCD41) to a CoreS3 over Grove and put CO2/temp/humidity on screen. The factory-fresh sensor read +30% high against a SwitchBot NDIR meter, so I ran FRC over a serial command to pull it in line.
A brand-new CoreS3 failed with 'SD Card initialization failed!' on the stock firmware. Tested two LAZOS cards: the 16GB never mounts at any SPI clock, the 32GB mounts but only writes at 10MHz, and a soft reset wedges the card until power-off.
