90% of third-party dongles are scams for the 5520. Because the 5520 uses encrypted SPI flash, a simple USB dongle cannot decrypt the password. Do not pay $50 for a USB stick.
Sites like bios-pw.org may generate unlock codes based on your 11-character system number [2]. On many Dell systems, you must hold Ctrl and press Enter when submitting these generated codes for them to work [2]. dell latitude 5520 bios password reset
: Locate the System Security or Security section. 90% of third-party dongles are scams for the 5520