screen is very dark and has a ton of burn in. it might be a nice project to repair and restore. residual crt voltage scares me to this day. gotta get some rubber gloves or something.
You need to discharge the CRT. It's easy and fun!
https://www.wikihow.com/Discharge-a-CRT-Monitor
(The photo for step 9 is a bit confusing, as it doesn't show the alligator clip attached to the screwdriver shaft.)
I grew up in the era of tube TVs (not just the CRT, the entire circuit was tubes). One of my earliest memories was being the family TV repairman, which meant pulling out all the tubes, going to the corner grocery with my dad to test them, bringing home the replacement for the bad tube, plugging them back in and the TV worked!
Dad showed me how to discharge the CRT, and we used the same tools and technique described in the WikiHow article. The loud "pop" it makes is really cool.
I regret not making that trade, the old Nintendo cabinets were beautiful, plus Popeye is a great game.