Connect one end of the electrical wire to the flat tip screwdriver

Connect the other end of the wire to the grounding screw

Using one hand only (place the other one in your pocket or behind your back) and the other not anywhere near the chassis, move the screwdriver behind the rubber shield of the Anode Cap. Slide it down until it touches the metal of the Anode. If your CRT was charged, you should now hear a "cracking" sound.

Not the sound of an explosion or anything as climactic, but definitely a cracking sound. If your CRT was discharged, maybe because it was unplugged for a awhile etc., you will not hear anything.