It sounds like your Lenovo ThinkPad T480 is stuck in a boot loop due to changes made in the BIOS related to Secure Boot. Here are some steps to help you resolve this issue:
Access BIOS/UEFI Settings:
Restart your laptop and press F1 repeatedly as it boots up to enter the BIOS/UEFI settings.
Check Boot Mode:
Ensure that your boot mode is set to UEFI if you're using Secure Boot. If not, switch it to Legacy or Legacy Support if available.
Disable Secure Boot:
Go to the Security tab in the BIOS settings.
Find Secure Boot and set it to Disabled.
Save the changes and exit.
Restore Factory Defaults:
If disabling Secure Boot doesn't help, you can try restoring the BIOS to factory defaults.
Go to the Exit tab.
Select Load Setup Defaults or Restore Defaults.
Save the changes and exit.
Boot Order Priority:
Ensure that your primary storage device (where Windows is installed) is set as the first boot device.
Go to the Boot tab.
Set your primary hard drive or SSD at the top of the boot priority list.
Save the changes and exit.
Clear CMOS (Optional):
If the above steps don’t resolve the issue, you may need to clear the CMOS to reset the BIOS settings completely.
Turn off your laptop and disconnect it from any power source.
Open the back panel of your laptop (refer to the user manual for instructions).
Locate the CMOS battery (a small round battery) and remove it carefully.
Wait for a few minutes, then reinsert the CMOS battery.
Close the back panel, reconnect the power, and turn on the laptop.
Check Hard Drive Connection:
Ensure that the hard drive or SSD is properly connected.
Sometimes, a loose connection can cause boot issues.
Repair Windows Boot Configuration:
If the system still doesn’t boot, you may need to repair the Windows boot configuration.
Create a Windows 10 installation media using another computer (USB drive with at least 8GB of space).
Boot from the USB drive by pressing F12 (Boot Menu) during startup and selecting the USB drive.
Select Repair your computer from the installation screen.
Choose Troubleshoot > Advanced options > Command Prompt.
Run the following commands:
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd
Restart the computer after running these commands.
Update BIOS:
If you manage to boot into Windows, check if there's a BIOS update available for your Lenovo T480 on the Lenovo Support website. Updating the BIOS can sometimes resolve boot-related issues.
Disclaimer: Microsoft provides no assurances and/or warranties, implied or otherwise, and is not responsible for the information you receive from the third-party linked sites or any support related to technology.
If you are going to modify BIOS Settings, please back up all your personal files first to ensure you do not lose data.
Contact Lenovo Support:
If none of the above steps work, it might be a hardware-related issue or a deeper BIOS problem. Contact Lenovo Support for further assistance.
Let me know if you need more detailed instructions on any of these steps.
