According to the instructions, the bottom button must be pressed for one second. After three repetitions, the SD card mode is activated. Here you can find the operating instructions, on the fourth page you can see the illustration: https://www.bedienungsanleitu.ng/gembird/bhp-led-01/anleitung?p=4 Otherwise I would have to ask you to contact the manufacturer directly if it does not work, there may be another option: https://gembird.com/contact.aspx