You have to turn the little black knob beside the on off switch ¡!

the O also means off

All you had to do was turn the preesure knob lol

I don't own this item in the slightest, however I'd try two things. Take out the battery, ensure there's no tabs that you are supposed to remove and then ensure that it's reinstalled properly. Try adding some liquid as the sprayer might be so smart that if it doesn't detect liquid it automatically shuts off and doesn't spray, however I'd think volt meter should still work. Regardless looks new and hopefully still within the return policy.

That's because you had it on and turned it off. The straight line is on so your doing it backwards and once it's on you have to turn the know on. You should remove the video since you don't know what your doing