Test for short between 5V and Ground:

Switch your Multimeter to “continuity check” and Probe on the two screws on the “screw terminal(X1)” for short circuit.
You could also youse the Resistance Measurement of your Multimeter, you should measure a rather high Resistance.
If you have a short look closely at your PCB an find the short! As soon you have no short it is safe to connect your moodlamp to the Power Supply.

Test the USB Connection.

Connect the moodlamp to your USB Port on your Linux Machine. Don't connect the Power Supply. Don't set the USBPWR Jumper.
As a result the USB IC4 FT232RL get's Power from the USB Port but the rest of the circuit is dormant.
The IC4 FT232RL is known by the Linux Kernel.

Execute tail -f /var/log/message in your favourite shell, as soon as you plug in your moodlamp you should see:

 
Apr  7 22:02:36 big32 kernel: [104624.674498] usb 1-3: new full speed USB device using ohci_hcd and address 3
Apr  7 22:02:36 big32 kernel: [104624.852065] usb 1-3: configuration #1 chosen from 1 choice
Apr  7 22:02:36 big32 kernel: [104624.852318] ftdi_sio 1-3:1.0: FTDI USB Serial Device converter detected
Apr  7 22:02:36 big32 kernel: [104624.852379] ftdi_sio: Detected FT232RL
Apr  7 22:02:36 big32 kernel: [104624.852469] usb 1-3: FTDI USB Serial Device converter now attached to ttyUSB0
Apr  7 22:02:36 big32 kernel: [104624.856573] usb 1-3: New USB device found, idVendor=0403, idProduct=6001
Apr  7 22:02:36 big32 kernel: [104624.856582] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Apr  7 22:02:36 big32 kernel: [104624.856590] usb 1-3: Product: FT232R USB UART
Apr  7 22:02:36 big32 kernel: [104624.856595] usb 1-3: Manufacturer: FTDI
Apr  7 22:02:36 big32 kernel: [104624.856600] usb 1-3: SerialNumber: A9005jBZ

Make sure you get no “USB disconnect” and more “connect” messages while the moodlamp is still connected. If that happens you have a bug.

if you unplug the moodlamp you should see:

Apr  7 22:04:10 big32 kernel: [104731.095092] usb 1-3: USB disconnect, address 3
Apr  7 22:04:10 big32 kernel: [104731.095092] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
Apr  7 22:04:10 big32 kernel: [104731.095092] ftdi_sio 1-3:1.0: device disconnected

• Consider resoldering your LED-wires to the PCB.
• Switch your Multimeter to “continuity check” and check if there is a connection between the “screw terminal (X1)” and the three big resistors. If yes: correct this! There should be no connection.