I've received my 3rd custom SAMD21G18A (Arduino Zero) board. Previous versions were working out of the box (including running the sketch), but my last prototype doesn't seem to start the sketch.
Since uploading a bootloader and sketch work without any problems, I can't figure out why a simple blink sketch isn't working. I searched for previous cases, but they were almost always AVR related or uploading gave some errors as well.
The voltage supplied is relative high, but stable @ 3.5v from a LM1117. The LM1117 doesn't heat up and receives it power from a 12v to 5v DC-DC converter. Note that another IC, a RN52 Bluetooth Audio module that is supplied from the same 3.3v rail is working fine.
Both the Arduino IDE and Atmel Studio provide no errors before/during/after code compilation and uploading.
Could it be a fuse setting? Changes in the last version of the SAMD21 bootloader?