Your game has two fat white switches on the left inside of the coin door. One is the high power interlock, which when enabled lets high power got to coils and flashers and when disabled cuts high power to the coils and flashers. And has absolutely nothing to do with the coin door open message.
The coin door open message comes up when the memory protect switch opens when you open the coin door. And the message goes away when you close the coin door or push the memory protect switch in.
So the issue is your memory protect switch isn't opening and closing, isn't working, or has a broken wire from it to the CPU.
It is switch #22 on your switch matrix. White wire red stripe and green wire red stripe.
If you go into Tests - Switch Edge - and push it in and release it a few times - does it register on the DMD ?
LTG : )