L displayed on the screen of any of the Uniden scanners with a 2 digit display means loss of programming information in the radio. The charge in the memory capacitor is exhausted, the charge can last anywhere from 30 minutes to the better part of a day depending on vintage and age of the radio.
Programing of the frequencies is needed and next time either leave radio connected to power source and use off switch or change batteries when the low battery alert comes on,
David Kb7uns