I have the original Smart Controller and when I check for updates it just sits and says checking for updates . When I use the DJI Assisatant it does not find the controller ..just says charging level is low I'm on ver 1.0.880
I am connected to Wi-Fi
My air 2 did update

Not 100%, but try the DJI Assistant 2 "Consumer Drone Series" version.  IIRC last update I did was with this.

Get the latest Assistent 2 for mavic from the DJI website https://www.dji.com/downloads/softwares/assistant-dji-2-for-mavic

See that the battery of your Smart Controller is charged (a low charge wouldn't let you install a firmware update)

Use the original charging cable that came with the SC. If you are not using the original cable, see that you got a fully wired (data) USB cable, not just one for charging.
Try to use a different USB port on your computer. There are a lot of USB standards and even thou they look the same, different USB ports can use different standards and chipsets.

Hi there. Thank you for reaching out and we're sorry for the trouble that this has caused. Can you please try to confirm what DJI Assistant 2 version are you currently using? Kindly please try to use the version specifically for the DJI Smart Controller to see if the issue persists. Please refer to the link below. Thank you.

https://www.dji.com/downloads/softwares/assistant-dji-2-for-mavic