If savemii only stays red, it means:
system menu/ios are screwed
boot2 is screwed
wifi module isnt fitted/broken
As you had an update, it sounds more like 1 of the 1st 2.
Your serial number has the possibility to be repairable via nand reflash without a backup, but i cant be 100% sure unless you open the Wii and get the date code from the hollywood chip as its around the time they fixed the boot1 exploit.