Take a look at this guide: Unresponsive keyboard fix

Do all the steps 1-3 of that guide and find the white connectors that are loose (within the red squares of the guide). Instead of using tape to secure them, however, do the following

Using some needle nose pliers, bend the staple so it will extend across the connector that is loose. Cut away the excess staple. Try to keep the whole staple covered with the electrical tape (I was lazy, and didn't cover the very tips, managed to not short circuit anything on the motherboard, but YMMV!)

Repeat steps 1-2 for the other loose connector