Hi
Just bought a new RB5009 to replace my hexS, which I need for something else, to serve as my home gateway.
As far as I understand, the RB5009 looks pretty bricked by now.
I will walk you through what I have done. Please bear in mind the word "winbox" is tabu..... I don't own a Windows computer neither I have a Windows VM neither Mikrotik has sent me a free Windows licence..... I do own a couple of Macbooks and plenty Linux machines.....

1) I connected the RB5009 to my LAN hoping it would acquire an IP through DHCP (192.168.27.0/24) to start programming it . According to my hexS, it did (192.168.27.58), but I could not connect to it with my macbook connected to my LAN.
2) I connected a macbook directly to RB5009 ETH1. I programmed the macbook net interface manually and I was able to connect to the RB5009 address on 192.168.88.1.
3) I programmed the RB5009 (webfig quick set) to have the fixed WAN IP that my hexS had attributed to it (192.168.27.58).
4) Still could not connect to it with my macbook connected to my LAN.
5) Connected directly to the RB5009 directly with a macbook again and verified I would only connect using the new IP (192.168.27.58).
6) I reset the the router, just for the fuck of it, as specified in https://help.mikrotik.com/docs/pages/vi ... andjumpers
7) I have lots of experience reseting MT routers. Reset never does what is expected. RB5009 didn't disappoint.....
After many resets with different time periods I could only connect to 192.168.27.58..... the address 192.168.88.1 never showed up again......
9) I could not get into the router webfig..... it said the user/password (admin/nothing) were wrong...... I never changed it......
10) The page mentioned in 6) says "Release the button when the green LED starts flashing"..... I don't know which LED they mean......
11) The same page says "Hidden Green LED behind the Reset button is USER LED"..... if they mean the USER LED in 10), I assume the LED is IN the brick BEHIND the reset button. I'm not opening the brick to check for it..... I'm not sure they know what the word "behind" means.......
12) After many resets, I can't connect either to 192.168.88.1 or 192.168.27.58 after manually programming the macbook net interface to connect to either interface.....
13) I have a brick!!!!!

Question: What can I do besides returning the RB5009 to the vendor?

There's this great and useful thing called WinBox. I didn't test it myself, but it's said that it works with Wine, so you don't need Windows to use it.

Pffff ..... what is all this ?

-MacBook OS does not run 32bit version programs any more since MacOS 10.15 Catalina. Many got in trouble with this. But now there is a 64bit Winbox version.
-I'm not a Macbook user , but told my friend just to install the free Oracle VirtualBox, in that VM environment run a demo Windows (90 days free). WinBox in Windows. He had no problems!

See comments

1) I connected the RB5009 to my LAN hoping it would acquire an IP through DHCP (192.168.27.0/24) to start programming it . According to my hexS, it did (192.168.27.58), but I could not connect to it with my macbook connected to my LAN. To what port? If it is 5009 LAN then IP addresses will conflict, If it is 5009 WAN, DHCP will be OK, IP address will be in your LAN IP address range, but no one can enter through a WAN port.
2) I connected a macbook directly to RB5009 ETH1. I programmed the macbook net interface manually and I was able to connect to the RB5009 address on 192.168.88.1. Yes, as expected
3) I programmed the RB5009 (webfig quick set) to have the fixed WAN IP that my hexS had attributed to it (192.168.27.58). OK. Won't help, but if only WAN IP is touched no problem.
4) Still could not connect to it with my macbook connected to my LAN. No, as expeced, it's a WAN port connected to your LAN. No entry in the router through it's WAN port.
5) Connected directly to the RB5009 directly with a macbook again and verified I would only connect using the new IP (192.168.27.58). What IP address did you change in 3)? The LAN IP???? I hope you did not
6) I reset the the router, just for the fuck of it, as specified in https://help.mikrotik.com/docs/pages/vi ... andjumpers Everything further says you did not do the config reset.
7) I have lots of experience reseting MT routers. Reset never does what is expected. RB5009 didn't disappoint..... ?????????????????
After many resets with different time periods I could only connect to 192.168.27.58..... the address 192.168.88.1 never showed up again...... Config was not reset, or you did reset but connect to the 5009 WAN port again, eg by using your LAN network. There is no access possible that way with the default config.!
9) I could not get into the router webfig..... it said the user/password (admin/nothing) were wrong...... I never changed it...... Only seen so far with 6.49.2 and blanc passwords.
10) The page mentioned in 6) says "Release the button when the green LED starts flashing"..... I don't know which LED they mean...... It's never specified in the docs, some LED will blink.
11) The same page says "Hidden Green LED behind the Reset button is USER LED"..... if they mean the USER LED in 10), I assume the LED is IN the brick BEHIND the reset button. I'm not opening the brick to check for it..... I'm not sure they know what the word "behind" means....... You should be able to see the glow of the hidden LED, along the Reset button. No? It is probably not used for the reset sequence.
12) After many resets, I can't connect either to 192.168.88.1 or 192.168.27.58 after manually programming the macbook net interface to connect to either interface..... You probably removed the 192.168.88.1 in 3), and the WAN port is no entry point. Connection 2 LAN interfaces is not wise if both have DHCP. MacBook directly to the 5009 LAN interface, and if DHCP fails, do "config reset", With all those reset without following the LED, who knows you got the device in CAPS mode or something like that."Reset" only while watching the LED blinking.
.

13) I have a brick!!!!! Not convinced. I hope you did not start NetInstall mode but it should not stay there either. (NetInstall starts by erasing ALL software). Running NetInstall in a VirtualBox might be a new challenge

I use this on MacOS: https://joshaven.com/resources/tools/winbox-for-mac/

You can update it to the latest version by opening the package contents and replacing the winbox64.exe file with the current version. It works great on MacOS.

Send it to me I will pay postage.

There's this great and useful thing called WinBox. I didn't test it myself, but it's said that it works with Wine, so you don't need Windows to use it.

Yes, it does work with Wine without any issues.

I believe Wine is used most often. But there was a period where MacOs refused 32bit apps and there was no 64bit WinBox

13) I have a brick!!!!! Not convinced. I hope you did not start NetInstall mode but it should not stay there either. (NetInstall starts by erasing ALL software). Running NetInstall in a VirtualBox might be a new challenge

Other hints to break open that "brick". The best tool, besides WinBox around is your hEX-S. It has MAC-level access tools to the RB5009.
If you connect the hEX-S LAN port to a LAN port of the 5009, and the 5009 still runs RouterOS, then you should see that MT in "IP Neighborgs".
IP addresses may conflict or be absent , no problem for "MAC Telnet".
If you get in that way either "System Reset Configuration" or open the WAN port by changing that ethernet port from WAN tot the LAN interface list, or by adding that WAN ethernet port to the bridge, or by resetting without default config, or by disabling the firewall, or by adding an input firewall rule for tcp port 80, or by replacing the DHCP server on the bridge by a DHCP client, or ..... or .... .

thanks for taking the time!

To what port? If it is 5009 LAN then IP addresses will conflict, If it is 5009 WAN, DHCP will be OK, IP address will be in your LAN IP address range, but no one can enter through a WAN port.
Well, I hadn't thought about that....

What IP address did you change in 3)? The LAN IP???? I hope you did not
Nope, never touched the LAN.

Everything further says you did not do the config reset.
Well, what is the RESET button for?

It's never specified in the docs, some LED will blink.
yep, some LED blinks, I think ETH1 LED.....
When it stars, ETH2 LED is ON, not blinking.....

You should be able to see the glow of the hidden LED, along the Reset button. No? It is probably not used for the reset sequence.
There's no LED behind the RESET button....

You probably removed the 192.168.88.1 in 3), and the WAN port is no entry point. Connection 2 LAN interfaces is not wise if both have DHCP. MacBook directly to the 5009 LAN interface, and if DHCP fails, do "config reset", With all those reset without following the LED, who knows you got the device in CAPS mode or something like that."Reset" only while watching the LED blinking.
I couldn't do "config reset" because I couldn't enter the router.....
I followed the flashing LED (ETH1, I think). Since I couldn't get the router to go to the original state, I started looking for the "behind LED"..... maybe there was another one.....

Now I got the router back to its default state. How? I performed a few more resets following the only LED I can see flashing, as I was doing previously.
Again, this has happened to me a lot, also with MT switches. Reset, reset, reset,..... until it actually resets......
Now that I will not try to enter it through the WAN port, I believe I will not loose it again.....

thanks

Send it to me I will pay postage.

Sure thing.
Give me your address so I can get a quote for postage.
You will have to pay me for postage before I send it to you.... I'm sure you understand.....

Send me an email.........