The 5520 has a known firmware bug where USB-C docks interfere with keyboard input on the password screen. Disconnect all docks and USB hubs. Use the built-in laptop keyboard only.
Disconnect the main internal battery cable from the motherboard immediately to cut all power. dell latitude 5520 bios password reset
: If the BIOS is set to "Strong Password" or "Data Wipe on Unlock," clearing the password might affect your ability to access encrypted data on the drive. Are you currently seeing a specific Service Tag suffix (like -8FC8 or -E7A8) on your unlock screen? How to Reset, Remove, or Recover BIOS Passwords | Dell US The 5520 has a known firmware bug where
Replace the base cover, connect the AC adapter, and turn on the laptop. The password should be cleared. connect the AC adapter