You probably have a "stuck/jammed" key on the kybd.. With no power present, run your fingers across the keys back and forth on all keys several times, hopefully this will unjam the stuck one. Again, with no power, turn laptop over and rap the back side a few times to see if anything falls out or unjams. Now, retry to boot and check results. If this doesn't work, then full access to dissemble the laptop maybe required, post back details on what your laptop is.

tada -----Willy Happy