Hi,
I am trying to reset the 433uah but no dice.

I tried the following:

1. Power off device
2. hold down reset button on the side
3. Power on device
4. Wait a minute
5. let go of the reset button

What am I doing wrong?

I have to reset as I cannot log into the box anymore, even through mac-address it is not possible anymore it says: "Timed out"

Please help.
Thanks!

Can you log in via the serial port?

button on the RB433 is not for resetting, you must use the jumper hole
http://wiki.mikrotik.com/wiki/Manual:Password_reset