Mac won’t take password

Follow previous advise - First.

Only as " fall back " position

Reset Computer Password  for the Administrator Account Password

Intel Computer

1 - Shutdown the computer 

1A - Restart computer and immediately hold the two keyboard combo Command  r 

1B - If using a Bluetooth Keyboard with Rechargeable Battery - Cable the Keyboard to computer for this unique purpose. Bluetooth Kernel may not load soon enough to execute the 2 keyboard commands 

2 - Top Tool Bar >> Utilities >> Terminal

3 - Type resetpassword as one word and no spaces

4 - Press Return key

5 - Follow the prompts and remember the New Password

Apple Silicon M1 / M2 Computer 

1 - Choose Apple menu > > Shut Down

1B - If using a Bluetooth Keyboard with Rechargeable Battery - Cable the Keyboard to computer for this unique purpose.

2- Do not  attempt a Restart to access this feature. The computer Must be Shutdown and pause for about 10 seconds before moving forwards 

 3 - Press and hold the power button on your Mac until you see “Loading startup options.”

4 - Click Options, then click Continue. 

5 - Top Tool Bar >> Utilities >> Terminal

6 - Type resetpassword as one word and no spaces

7 - Press Return key

8 - Follow the prompts and remember the New Password

Try this to reset the password on the MacBook Pro:

Reset Your MacBook's Login Password

Note you'll need his AppleID/password for this process.

Hope this helps.