I know this wasn't asked, but in case this is useful to future readers..
When bringing them back online, it is good to power up your MX as soon as it is racked and connected to the ISP. Connect and power up the MS250 next and you will have everything (the rest of the building) back online except devices connected directly to this rack. It also provides, should you need it, connectivity from your laptop to the dashboard.
In regard to the stack, power on sequence should not matter. As a personal preference, I bring them up "top to bottom" as seen in the rack. Typically, as each one is being cabled, I will have it booting up so I can watch the boot sequence lights and know it is communicating with the dashboard. By the time the last patch cable is connected, the dashboard should be all green again.
#ProTip Spread your AP and MV connections among your switches to minimize impact of a single switch going down. For example, ports 1-6 of each switch in a stack or closet would be dedicated to wireless and/or surveillance.