The red light is an indication that Rollo has a problem with your label.
Performing the Automatic Label Identification can resolve the issue.
Please choose your printer for the recommended steps:
Rollo X1040 Wireless Printer
The Rollo wireless printer is designed to automatically calibrate the labels, by simply inserting the labels through the back of the printer.
In some cases, you may also perform it manually by following the steps below:
For more information please refer to: https://www.rollo.com/wireless/
Rollo X1038 USB Printer
Most likely, Rollo needs to re-learn your label.
Please ensure there are multiple labels available to Rollo and then run the automatic label identification. Simply press and hold the top circular button on Rollo until you hear one beep. Rollo will then move the labels back and forth to learn the gap and other label properties.
To watch this in a video, please see: Setup Rollo for First Use
If the automatic label identification does not work or the red light remains, please turn off Rollo using the power switch on the back and then turn the unit back on.