I have ordered USB Keyboard with numeric keys to stop playing each few weeks with batteries in my bluetooth keyboard. But what a surprise - after updated to latest version of OSX El Captain the keyboard stopped to wakeup from sleep and I was not able to use it in any way.
Nothing helped what I have seen on Apple support forums:
- connecting to other USB ports, removing all other USB devices
- disconnect, connect after few minutes
- reset NVRAM or other types of OSX storages
.... THE SOLUTION:
Even it looks stupid and has no sense, I have connected between macbookpro and the keyboard new USB extension cord and keyboard started to work again.
If you have the same problems, its worth to try it :-)