SOS Unrecognized keyboard, unpowered

good evening,

following power outage (i not know if before worked), restart of mac, turns on correctly arrow frozen in top left of imac screen , neither mouse nor keyboard works.
details
- in keyboard , wired mouse
- tested mouse , keyboard on friend's imac, works perfectly
- mouse powered not act on arrow on screen
- keyboard not powered uppercase diode not turn on
- tested usb ports, seem work
- tested keyboard putting usb extension, nothing .....

admit not know anymore .... do
have idea thank in advance

bp
bplabmac

 

start smc reset. turn off imac, , remove plug mains, , rear of imac. let stand overnight, connect mains power cord, mouse , keyboard directly imac usb ports. power on , fingers crossed.

no joy navram reset, known in old says pram reset. have read of link ideas:-


https://www.macworld.com/article/2881177/macs/how-to-reset-your-macs-nvram-pram-and-smc.html

 

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