[sudo-discuss] Door and Keypad Update and Need Help (Electronics Knowledge)

Only last night I got the keypad running again, and was trying to insultate the wires to improve its uptime. So I coated two connections between the rasberry pi and the relay which is attached to the door. After coating, it seemed like I somehow failed these connections, because the software exited normally (opendoor.py was still being called and sent success messages), but the door was not opening. I tried to unglue them, but when i was taking off the glue, I disconnected one of the wires that was at this 3-way junction. Then I resoldered the wires but to no avail. So everything is totally broken now. Can you help with a multimeter and a solder gun Monday to hunt this down? I don't know how to test if there is current at point, nor why the two wires would split coming of the rpi, and then both go to same relay. BTW what's a relay (i've only heard the term)? Please tutor me in the ways of righteousness, notconfusing 7074787023