Troubleshooting: Dymo Labelwriter won't switch on or blue light is flashing

If your Dymo Labelwriter 400 / 450 / 550 printer won't switch on (ie. the blue light is off, and the feed button has no effect) then there are a number of possible causes - loose connection, faulty printer, faulty power supply, blown fuse, faulty outlet or of course someone unplugged the machine or switched it off at the wall! So let's go through some troubleshooting steps:

  1. Firstly, if you've not used the printer for a long time and you've dug it out of a box or cupboard full of cables and other devices, make sure you've found the correct power supply!  The labelwriter power supplies consist of a power supply unit with a fixed cable at one end (that goes to the printer), and then a separate power cable (that plug into the power supply at one end and the wall socket at the other).  It wouldn't be the first time a customer has damaged their Labelwriter by mistakenly using a power supply from a different device.
  2. Then check that the cable from the power supply is firmly plugged in to the printer, that the power cable is firmly plugged into the power supply, and that the other end is plugged into a wall socket that is switched to on.
  3. If the machine still doesn't power on, try a different "known working" power socket just in case the wall socket is faulty (again, it wouldn't be the first time we've seen this problem)

If the machine still isn't powering up it is likely that either the power supply or printer itself is faulty, and you would need to contact Dymo Tech Support (via their website) for help.


If the labelwriter is on, but the blue light is flashing, this usually indicates a label problem - such as the labels have run out or are not loaded correctly, or in the case of the 550 series that the labels are not recognised as Genuine Dymo labels.

  1. Make sure the labels have not run out
  2. Make sure that there are no stuck or jammed labels
  3. Press the feed button to see if a label comes out
  4. Check that the labels are the correct way around (they should be print-side down when coming off the roll into the feed slot)
  5. Check that the labels are pushed up against the left edge of the spool, and that the right part of the spool has been moved up to the edge of the labels so they are secured (not too tightly) in place, so they don't slide about
  6. If it's still not working, try a different roll of genuine Dymo labels
  7. Unplug the machine and plug it back in

If the machine still isn't printing, and the light keeps flashing, please contact Dymo Tech Support (via their website) for further help.