Hi, please check Pin 6 of ATmega, it should read as a positive voltage, around 4.5V - 5V when it’s powered on.
You can use the MIDI OUT pins marked with green arrow for the black multimeter probe.
If you read a value close to 0V, it means that the ATmega is not running (like due to XTAL issues) or that an unprogrammed chip slipped in during packaging of the kit.