OS Sierra escape

[Andrew B]

i have a MacBook Pro mid 2009 which I recently upgraded to Sierra. Upgrading via the download didn't work but I reckoned that as the MacBook was "borderline" it was worth using the hack. Everything was fine for about 10 days, then I lost trackpad, keyboard and peripheral access (i.e. USB). I didn't have a recent Time Machine backup, and didn't want to lose anything on the boot drive. I have 2 hard drives, so after some head scratching, downloaded El Capitan onto a thumb drive on my iMac and installed this on the 2nd hard drive. The next move was to do a Time Machine back up, but OMIT THE SYSTEM FILES. El Capitan was then clean installed on the boot drive and the Time Machine backup restored. It may all seem a bit obvious, but I spent a long time searching for help, without success, so hopefully this info will help anybody else with a similar problem