If you are getting flashing red lights when the pedal boots up this means the SD card is not recognized.

There are a number of things that will trip you up. Please make sure each of these is true.

1) The card you're using is high capacity. You can tell if a card is high-capacity if there's SDHC written somewhere on it. SDXC cards should work as well. 

2) The filesystem is FAT32. How you determine this depends on your computer's operating system. If you have Windows, right click on the SD card in a file explorer, and select "Properties". It should say "File System: FAT32".

3) The firmware file is in the root directory of the file system.

4) Make sure the card isn't locked.  There will be a switch on the left side of the looper.  This is prone to breaking off and rendering the SD card unusable, sometimes an SD card with a broken switch will work sporadically.  

5)Are you having problems with your computer reading the SD card?  If you're using a Mac with Big Sur installed there are a number of reports online about SD card read issues with Big Sur, a google search may be the best way to determine the latest fix for Mac card read errors.  

Here are a couple cards we tested that we know work: 

UPDATE:  The Lexar card pictured will work to update the pedal but will not work for the looper

Also, we do have a SanDisk 16GB card (pictured below) that doesn't work, and we don't know why. And there's a couple other SanDisk cards that customers have reported not working. We haven't gotten to the bottom of that mystery yet. So if you're having issues after following the 3 steps above, and your card is a SanDisk, please try a different card if you can. Hopefully at some point we solve the mystery.

Email support@empresseffects.com if you have any issues.