TomGeorge:
Is that with the button pressed?
Can you measure the voltage at the button pin12 on the Nano with respect to gnd, with and without the button pressed.
Thanks.. Tom...
Hi Tom, testing the BTN now. I've removed the switch, because for some reason it stopped working and I think it somehow killed my Arduino because it kind of acted strangely as well.. Luckily I have spare Arduino and I'm not using the switch untill I understand it better.
The new button sends in 4.8V to the Arduino. wow.. Now i get 4.8V out of D11 as well! Alright just put everything back together and it works!
But... I have to remove the diode I've put on for the solenoid, that's super weird. It doesn't work whenever i have a diode on it.
EDIT:
Oh shit, just tested it some more and the diode emitted a little smoke/vapor. It's hot.