"Force Lock" is one of the options available while Lockpicking in The Elder Scrolls Online
Forcing the lock lets you attempt to automatically try and break the Lock open
This option also shows you the probability you have at succeeding. The higher this number is, the better your chance of forcing the lock open.
If you fail to force the lock, your Lockpick will break and the chest will remain locked for a set amount of time before you can attempt to lockpick it again.k if you fail at your lockpick attempt