Possibly the bluetooth module. However if the bt module went bad priiloader would still work, also savemiifrii will load the recovery menu. So test priiloader again, turn the wii off, hold reset, turn the wii on and keep holding reset. Also if you have a gc controller you may like to test savemiifrii. One other thing to test bt module, which may not work with other hardware issue. Download [
www.mediafire.com] have a look at the readme. Basically you replace ppcboot.elf with one of the channel forwarders. This will load those channels via bootmii. If the channel loads your bt module is working fine, and you should be able to sync your wiimotes.
Other common hardware issues- wifi module and dvd drive. Also could be anything bad on the mainboard, which can minic such symtoms.
It possibly could be a corrupt nand. Load bootmii and make a new nand backup of the bricked wii. Then check the backup with nandbincheck, run from the shell console.
nandbincheck nand.bin -all -vvv
http://www.mediafire.com/?9778sgmybexww1o
Nandbincheck will scan your nand.bin for erros. If the nand img is bad it should be staight forward. Post the output of nandbincheck here and we can have a look at it if you like.