Game & Sound But No Picture

@siradam as you already know this is a CRT (picture tube) that works with some pretty high and lethal voltages. You do want to make sure that you are utilizing the properly safety precautions before working on this. This "I am not very tech savvy and this is out of my league" is good to know. That means you are aware of needing somebody with some experience to fix that,

This sounds like an issue with the power board. There are multiple fuses that you will need to check. Check the capacitors for bulging and leaking as well. Do a visual inspection of your power board and post some well-focused, large images of that board with your Question. That way we can try and help you out. Adding images to an existing question

Do not poke around this without properly discharging the tube and the power capacitors!

Use the Vectrex Service Manual and start by reading the circuit description starting on page 8. It gives you a better understanding on how it works. Here is a CRT Safety Guide from Apple but it is the same for all CRT's. Use common sense and be careful!