Accelerated reboot under a "Ruler"? Funny you should put it that way.
Rulers are literally "rulers" because they are expected to measure out everything from official decrees down to actual standards of measurement for things such as weights for grains and sand, volumes for beer and oils, and lengths of geometric value so they can measure a new construction project or the depth a guillotine must fall to be considered humane. To reboot from a place where intangible numbers can be placed onto real world objects by a "ruler". It was this latter ability to apply abstract or intangible concepts such as dimensional measure and mathematical concepts that would differentiate a Ruler from a petty Tyrant that could only usurp the kingdom a Ruler built just to run it into the ground in short order by the decay springing from the loss of the scientific first principles of engineering, music, geometry and arts.
In short, a tyrant's or unjust/incorrect "ruler's" ineptitude toward the aforementioned first principles will eventually undo all previous advancements due to foundational decay of basic knowledge of things that can't be stored like a jar of peanut-butter under a mattress. Any ruler who restores without it can have all the leftovers from his previous world but he and his people will still fail in any long lasting period of rebuilding acceleration from any other means.
That being said, if there would be any accelerated reboot due to anything other than "true first principles", based on the ability to produce a standard system of measures using only a few basic items from nature that were never themselves produced with any man made system of measure (such as the modern inch, yard, milliliter, Fahrenheit, kilometer, Gauss, Coulomb etc.) then, the accelerated reboot would be very short lived as all those units of measure would fall out of calibration, one by one, and eventually come down to many Tyrants (dressed as able Rulers) decreeing that a foot is based on his own right foot and a Yard is base on his stride. Eventually, even architects for the same Tyrant couldn't build identical stockades for the unruly subjects in distant cities unless they had to share the same ruler in fear of having to tell the Tyrant they needed him to take off his shoe again to avoid construction delays. (for measuring a 1 foot ruler and accurately dividing it up into fractions of inches; Making copies of copies builds up errors fast, especially over generations after the king is dead!)
So I'd say, besides the use of the human body to do the work its mind creates for it, the first thing needed for a reboot that could be accelerated and sustained by some means besides leftover technology that would need calibration by people who can not remember how to make a yard stick or accurately measure two nautical miles by two different people in two different places well.....
they'd first need to be able to reliably produce a yard, meter, foot, cubit, pound, 1 degree of Arc, etc. from a previously non-graduated source via a simple and repeatable method that is not based on one person or the use of timing devices such as pendulums. I mention pendulums because someone has already came up with an ill-conceived way ancient peoples produced the megalithic Yard that built Stonehenge that relies of a huge construction of a circle, astronomically timed observations and a good bit of "do-over, I lost count after 99 passes of the pendulum" to get it right! That method, although plausible, is not practical nor necessary.
A megalithic yard, and also a cubit of any varying fractional standard desired, can be produced in less than 60 seconds with 1 primitive tool on any day of the year. Once the method and the relationship of the geometric principle behind it is understood it can be done inside a room as well as outdoors. From this method all ancient forms of measurements and weights were made by "Rightful Rulers" until the knowledge slipped away into a Tyrant's shoe. Without knowledge like that, any reboot (accelerated or not), will not be sustainable. Anyone with knowledge like that deserves to be a "Ruler" for it is what literally built civilization.