The Americas have been occupied for tens of thousands of years. Check your facts.
In fact, don't you have some sort of celebration of the fact that you super-ceded them involving pumpkin pie? 
I first heard the 100 year/100 mile phrase a long time ago and it goes a long way to explain our differences.
I was of course just leg pulling, but some very funny responses 
Back to the topic in hand. It's interesting how such a mundane problem can throw up so many problems.
My original idea of a ultra slow mechanical clock that effectively used the moon as a power source, and then activating the electronics at the last moment was intended to keep the electronics turned off until required thus preventing FWAT, this included the power supply.
Someone mentioned redundancy, well, yes of course, but one could take this a stage further and rather than simple majority voting, one could maybe use a learning (repairing) neural net that could "energise" new circuit parts as others failed. For time keeping, again use say a solar event (day) to count.
Power supplies are a problem if self contained, but, since we are in a loft of a house, why not use main power and indeed, every 10 years it could request human intervention to "swap-out" circuity.
A friend of mine has a small (electric) lamp that he keeps burning in memory his mother and is thinking of emigrating to Oz, and wanted to power the lamp during the the move and sea voyage. His requirements were very stringent the light must not fail! And yet when I asked him what currently happened about power cuts, or the bulb blowing, he went quiet and didn't have an answer.