Is there a way to access BIOS on a used Lenovo Ideapad G580 2689 ?

[m654321]

Can you log into Windows 8.1 with an administrator account?
If you can login (know the password) is the account an administrator account?
If it is an administrator account i/e user name joeblow with administrator privileges hold the shift and control keys down together and open the command prompt not releasing them until the CLI opens. At the elevated prompt type: net user administrator \active:yes  This will activate the default passwordless account used for Windows installation. Restart and try the options again.

TC

Thanks TC.
This UEFI laptop came to me with Win10 on it: the Lenovo support website showed that the G580 (made in 2012) isn't supported by Win10, only drivers & apps listed up to Win8.1 64-bit. So I installed Win8.1, using another Windows activation key that I had.

Then, I installed both a Sys Admin (password protected) and my normal daily User account (no password, set up as auto-login).
So no problem with accounts set-up.