Need Help With First Soda Machine: DNCB 501T/MCB-8

I just bought a Dixie-Narco DNCB 501T/MPC-8 for $150. The previous owner said the machine just stopped charging people for the soda, and dispensed them for free.

But the first issue I’m having is that I can’t seem to go through the menu how I’d like, to set prices or check total sales etc, and it seems to do what it wants.

After plugging the machine in and opening the face, the display screen started going up in $.50 increments non stop, up to $99.50 and then repeats. At some point, unsure if it's cause I hit buttons 1 & 2, if so it didn't react instantly, the display goes through all the menu options for a bit before doing it all over again.

I followed the instructions from a member of another forum who states:

"You start by pressing the service mode button on the board and you should then see S-T on the display for Sales Total.

Hold buttons 1&2 together (very touchy and particular) to move through the menus.
Press 1&2 to show HPt which is Historical Product Totals and the total cash through the machine (non-resettable).

Press 1&2 again to see HPc for Historical Product Counts. With this on the display you can view vend totals by column.

Now is the first quirk in the MPC programming.

To move to the next group of menu items you must press 1&2 together in successive turns to get back to HPt at which time you must HOLD the two buttons for 5 seconds until the display changes to C-D for coin dump.

Now pressing 1&2 will move through the 2nd group of menus, the first of which is ESC for Escrow.

The next item is S-P for set price. When S-P is on the display you may press any selection to adjust it's price.

The last menu is n-t for Motor Test. With n-t on the display you may press any selection to run one test vend of that motor."

After pressing the what i believe to be the service button (a long, thicker, white stick looking button, sticking out from board) and then pressing 1&2 at the same time to try to get the menu to appear, the display seems to react as it stops going through menu options or increasing the price on the display for a second or two. It doesn’t seem to go through the menu on demand when I hit the buttons, but just slows or pauses the display for a couple seconds.

I don't even see the total sales of the machine at any point after hitting the service button and pressing 1&2, which is what's supposed to happen from what I've read. But at some point with me messing with the buttons for a bit, I did noticed I did change the price a little as the display was increasing from $1 to $1.50 to $2 etc. But after messing with the buttons it’s now jumping from $1.14 to $1.64 to $2.14 etc. But I can’t seem to get the machine to react like this and change the prices again, unintentionally or not lol.

The previous owner said that the machine stopped accepting money and just started dispensing the sodas for free, but I can't even seem to go through the menu on demand and the display/menu/machine does what it wants. I see that the person on the other forum said that these machines can be touchy. But I can't even get the total sales to pop up. Mine is about not being able to control the machine/display at all. I feel like there is something more wrong than just a wire or relay, but I know that this is a machine where if one thing goes wrong, a lot else can go wrong as well.

I'm just wondering if the issue is with the MB and this is why it's acting like this. But then again I know nothing about vending machines and am doing this as a hobby and if possible, for some cool passive income. I already feel badass owning one, spent 1 1/2 hours looking and playing with it in 30 degree weather today. xD

Any help is greatly appreciated, Thanks in advance!