If you are working over the serial port, use the ascii number. Only use the same number - and I recommend using ascii '1'. Note that you will probably need a bootable CD to be able to do any maintenance - if that is your goal.

Note also, a 43P-140 will not boot AIX 5.2 or higher - only AIX 5.1 and lower.

To begin with, depending on your setup, you will need to press F1, or ascii 1.

If you have a graphics adapter installed, attach a graphics terminla and a keyboard. Generally, this will be the default console. OR - when you have a graphics card - DO NOT attach any of following: display, keyboard, mouse - THEN the 43P should default to tty0 as console.

btw: 5 means boot using service boot list, only option 1 means go to SMS menu (or F1, F5 with graphic and older BIOS/firmware).

Once you get into console/maintaince mode you can activate a root prompt. If you create a new passwd file, with just an entry for root

You can then use the passwd command to set a new password for root, and reboot. And do you maintenance while booted.