Startup testing is what you do before starting up the equipment. So it traditionally involves, among other things, point to point wiring checks. Two other tests usually done as part of startup testing are ground testing and insulation resistance testing. Neither is done with power connected.
Of course, many other tests may be performed. And it may be the case that power is actually available at some or most equipment. Don’t assume anything is de-energized, even though most of the tests in this phase don’t involve power.
The words testing and texting sound similar. But make sure they never occur simultaneously. During startup testing, you must stay focused on your work. Any distraction could mean you leave on a stretcher.
Today, many people have a compulsive need for instant communication. Maybe your boss wants to be able to send you a text message asking how things are going. That’s fine. But your boss needs to be aware that your phone is not only off, it’s back in the truck.