Well, if it were me, the first thing I would do would be remove the batteries and desolder the battery holder holder and get it off of there. Then I would neutralize the alkaline leakage on the board. If you have never done this, refer to this post
https://pinside.com/pinball/forum/topic/stripping-battery-corrosion-with-a-strong-acid
I have had great success with this method. This alone might fix your problem because that alkaline on the board can causes shorts and make the board do weird stuff. However, I noticed from your video that the 20V and 50V LEDs are not lit up on the driver board so there may be a power supply issue but I would clean that battery leakage first and see what happens and then go from there.

man!! thats a lot of corrosion that could be your main problem,also corrosion spreads like wildfire it hides behind the battery holder-a real mess

Do you have the manual? my reason for asking is it would be a good idea to replace all the fuses.then reseat all connectors and ribbon cables.but like i said before that corrosion is way too much.do you have another good board you can throw in there?damn shame a game like this just sitting for 1-2 years with no love

Here is a picture of the driver board with the LEDs circled.

io_board_led (resized).jpg

Your CPU board need be fix.Look how much corrosion you have around IC's next to the battery holder.You must replace them and also check and the one with the socket.It may have some under it too.Do this and for the yelllw caps and resistors.First do this things and after that we can continue to talk if there more problems.

right,if i were the owner for the time being i would throw in a new board and get it up and running.Thats a lot of corrosion and like you said on and around IC's,sockets ect.

best thing to do is start a new thread about buying one and someone will contact you or post that they have one.i can help by bumping up the thread to stay on top so fellow pinsiders can see.

But this corrosion is not so bad and can be fix easy.
Find someone to do it,it will be more cheap than buy used board.

it's bad and corrosion does not just wipe off and go away,it hides really well and spreads.even if you give it a great cleaning it most likely/will keep popping up

If you find my threads where I had several projects with the corrosion you will see that if you someone know what to do it will do it right and no corrosion will left.
I don't talk for cleaning.This is not the way.It's more different method.If I were in US I can fix this board but you are too far from me.

Oh ok,cool im sorry i didnt know you had put up threads about it

I just say that the damages are not so scary and can be fix instead to find some board that will cost 300$+.
There are many members that can do it.

Right if the owner has some free time why not

It's not more 3-4 hours job.I can see 2-3 ICs(U214,U212 and eventually U200),two sockets(RAM and CPU IC's) and 4 resistors and 5-6 caps.Check the traces and job done.
If I can see well the corrosion is to U200.
These boards are not easy to find also.

Missing +20V and +50V can be from opened coin door.