2012 Macbook pro password issue

[WW4B]

Hello, my daughter has a 13" 2012 macbook pro running Mohave. Yesterday she issues where her password would not work. It boots and starts up fine up to the log in screen but when she enters her password it shakes indicating incorrect password was entered. Rechecked that caps was set properly and rentered again..same issue.
She then proceeded to reset her password. Macbook was booted in recovery mode, selected utilities, terminal. Typed resetpassword and pressed return. Reset password screen pops up, entered password, message stating password was successful and to restart. Restarted, load bar present, to log in screen and enter password.
Again it just shakes. Has anyone experienced this before. Could she have unknowingly messed something up ? Any suggestions ?

[chscag]

Do you have an external USB keyboard that you can attach to the MacBook Pro? It could be that the keyboard is defective and not responding with the correct keys. Were there any liquid spills on that keyboard, lately or a while back?

[WW4B]

Thank you for the reply. Attached an external keyboard via usb and still experienced the log in issue. No liquid spills on the keyboard or laptop itself lately or ever...we learned our lesson the hard way on my eldest daughters macbook pro a couple of years back.
However, went back into recovery mode and reinstalled mojave on a whim. When completed and the laptop booted to the log in screen, the same password as always used was entered and viola we were logged in and up and running as if nothing ever happened. This log in issue was evident for over a day and a reinstall OS corrected the situation.
Glad its fixed....but curious as to why this happened. Any comments from the forum?

[chscag]

That definitely is one of those... "What happened"? Glad to hear her MacBook Pro is back to normal. It could have been corruption of her account information or just about anything that interfered with the password input. Sometimes a reinstall of the operating system can cure a bad account and sometimes a new account has to be created. By the way, that would have been our next suggestion. Also, I'm glad to hear that you are aware of the damage that spills can cause.

Have a good one.