One row of keys not working

The row of keys from "Clear" all the way to "Enter" (the most right row on the keyboard) of my Texas Instruments ti-83 plus aren't working. Also, the directional keys aren't working. Strangely, a few days ago, they still worked nice as normal. I already opened the calculator to find maybe any dirt or contaminated contact (cleaned them with rubbing alcohol), but still no functioning keys. Battery are fully charged, and the rest of the keys just work fine.

Does anybody know how to fix this problem?