Hi rexardiente,
Thanks for posting in Apple Support Communities.
We understand the Shift key is not working. Check that other functions haven't been assigned to the keys. If this doesn't address the keyboard setup, it would be best to have your computer inspected at an Apple Authorized Service Provider or Apple Store.
You may have accidentally set an option that changes how your keyboard operates.
* Choose Apple menu
> System Settings, click Accessibility
in the sidebar, then click Keyboard on the right. (You may need to scroll down.) Make sure Slow Keys is turned off. If Slow Keys is on, you must press and hold a key longer than usual before it’s recognized.
* Choose Apple menu > System Settings, click Accessibility in the sidebar, then click Pointer Control on the right. (You may need to scroll down.) Make sure Mouse Keys is off.
* Choose Apple menu > System Settings, then click Keyboard
in the sidebar. (You may need to scroll down.) Click Edit next to Input Sources on the right, then turn on “Show Inp
You can find these steps in If your Mac doesn’t respond to key presses - Apple Support.
Contact Apple for options.
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Regards.