A blinking red BATTERY indicator means a charging error has occurred. The WL-20 / WL-20L may pause charging to protect the rechargeable lithium-ion battery in the following cases:
- The transmitter's internal temperature is too high. When the internal temperature falls, the BATTERY indicator lights orange again and charging resumes. Remove the transmitter from the receiver and wait a while before using it again.
- The room temperature is above 35°C (95°F). Use the unit in the recommended ambient temperature range of 10–30°C (50–86°F).
If the above measures do not resolve the issue, the unit may require repair. Contact your local dealer or a Roland customer support (Backstage, Roland Account required) for assistance.