I bought S9 that has Hiveon software on it, since I mine on slushpool, i changed the jumpers, flashed a 16 GB SD card with the SD firmware, however the router doesnt pick up the S9.
Let's hope you did not brick the control board, where did you download files which you used on the SDcard to perform the flash? did the 2 LEDs flash a couple of times when you did the flash? also do remember to change the jumpers to their original location or else the miner won't work unless you have a Bootable firmware on the SDcard which I doubt.
If this is Braiins OS one very common mistake newbies make is assuming that booting the sd card "flashes" the firmware. No, it doesn't, if you remove the card without logging to the miner and using the flash to NAND option, its never flashes. The point is you can use it from sd without ever flashing it to the miner for testing purposes or if the NAND is damaged. Works the same except no self-updates.
The other common mistake is, believe it or not, not clearing the browser cache or try a different browser. The likes of Chrome are annoyingly persistent with their now stale cache data from the earlier firmware.
Also, very often the ip address changes, and you have to find it again, either from your router or using a tool such as Angry IP or nmap. No, Bitmain scanning tool doesn't work.
Bitmain recommends using less than 16gb micro sd cards. This roughly tell us they are not using sdxc capable chips and can read sdhc at best. But in my experience, it is best to stick to plain old sd, which means under 2gb. Often 4gb, 8gb or such work, but its best to go as small as you can, and sometimes just changing the brand of sd makes the difference. You can thank Bitmain (or Xilinx?) for that, they don't use laptop quality
microsd "tf" reading.
If it doesn't boot no big deal, flash another sd card and try again.
PS: You have to flash the .img file into the micro sd card using a tool like Balena Etcher, Rufus or dd.