Yes, that more for getting into netinstall mode.
Also, I would remove all cables other than power and the one you are connecting to the RB5009. It almost seems there may be an ip conflct. Does your network have any other devices in the 192.168.88.0/24 network?
Some relevant posts that corroborate what jaclas said:
This is the relevant help page (specifically “Resetting the RouterOS configuration”)
https://help.mikrotik.com/docs/spaces/ROS/pages/24805498/Reset+Button
In my (limited) experience it works. It can be finicky, but it does. Things to watch out for:
Press and hold the reset button without releasing it while powering up. This can be difficult while plugging the device in - feeling the correct pressure on the button, etc. Because of the recessed button some sort of tool is recommended, People h…
(no matter, but DNS and gateway is completely useless on netinstall)
Disable all network interfaces (wireless, bluetooth, vpn, something), not mind you think some interfacee not mind, except ethernet used for link to RB.
Use netinstall 32 bit, not mind if you pc is 64.
Keep button pressed when device is off, Keep button pressed when you connect power, do not release button until do not appear on netinstall. No matter how many seconds are needed. Obviously if you wait more than 60 seconds, som…