Inspiron 3520 broken power supply cable connector on motherboard

In the Inspiron 3520 the power cable connects to the motherboard via a small slot and is held in place by a plastic bit that is pulled up to release, and pushed down to secure said cable. In the process of upgrading the processor of this machine i broke and lost this little up-down, unlocking-locking piece. I have tried unsuccessfully to keep the power cable in the slot using electrical tape, and also by using a small plastic bit as a shim behind it. After several attempts i am still unable to start the machine in the usual manner. During these failed attempts at securing the cable i accidentally discovered that a small screwdriver inserted into the slot where the power cable is meant to reside will hot wire the machine on. I have replaced my keyboard and now do not reboot or shutdown. An iffy fix at best. I am looking for suggestions as to how i might secure the power cable onto the motherboard so that all works properly? Looks like the power connection is on one side only so some kind of shim behind the live side forcing it to connect seems logical, but hasn't worked for me so far. What am i missing here? Or should i buy a dead motherboard to get the missing piece that i don't even know can be put back in place? Solder it in place? Any suggestions much appreciated!