Right when the screen turns off, move your fingers quickly to the power button and the volume up button. Hold them and see if that gets you into the bootloader. l
In order to enter recovery mode from a reboot, you need to immediately remove your fingers from the volume down and power buttons when you see the Samsung Logo, then you need to quickly tap the volume up button. You can also wait for the battery to deplete, charge the phone and start by using the power on & volume up buttons.
Perhaps when you reset it, it might be best to not put any security lock on it or at least, if you do, you write the PIN down somewhere and keep it yourself or keep it in a note on *your* phone. If he's elderly, he's bound to forget it again and you might want or need access to it when his time on the mortal plane is over.
------------------------------------------------------------- Please mark any response that helped you as your solution. -------------------------------------------------------------
No, it will not. Only if you do it from within the OS, which the OP cannot get into. It will ask for your Google and Samsung account credentials when you set up the phone after the reset, but not to reset from recovery mode. The OP said their dad forgot the PIN to the phone, not the password to Google. Resetting the phone is the only way to reset the phone's password/pin/pattern if they were forgotten.
------------------------------------------------------------- Please mark any response that helped you as your solution. -------------------------------------------------------------
