You tried exactly as written, switched off, inserted the ISB with the supplied files and and kept the service switch (at back of amp) pressed for more than 30 seconds after switching back on? And then released the button and waited at least 30 minutes before net reset and system reset? From what others have said the only reason that would not work is if you hadn’t followed the instructions correctly.
These instructions here with photos should help from paulguk How to do a full reset and reload of firmware - #28 by paulguk
USB stick needs to be FAT32 formatted
Otherwise, Precisely what did you observe whilst doing this?
do you still get Arc v0 and Net v0 or just in 0.0.0.0?
Are you trying to connect via the Ethernet cable to your router or wireless?
If wireless, do you have an android or Apple device on the same network?