Hi LizzyP9897,
Thank you for reaching out Microsoft Community. We're sorry for the trouble this may have caused. I
There's only one thing we can do for us to determine if this is already a hardware display issue and that is to check if the yellowing part of the screen appears in UEFI Settings. The UEFI Settings is an outside Windows environment
and if the screen display you're encountering right now shows in UEFI, then this confirms that the current issue you're experiencing is already a hardware related problem and this can't be fixed anymore by any troubleshooting.
To access UEFI ,kindly check this link https://support.microsoft.com/en-us/help/4023531/surface-how-to-use-surface-uefi for
details.
In the event that you see this on UEFI, then the best resolution I can suggest is to have it replaced. I know that it's not a perfect time to get it replaced since you're using this device for school and for immediate replacement, this can only
be done at MS store if there's one of the same configuration available. But, due to the current global health crisis, our MS stores are not available for appointment and are not open for safety reason. So, it's best to
contact support right after seeing this display issue in UEFI to have it reported and if your Surface device is still in-warranty, they can somehow check any available options to get it replaced.
If this answers your question, feel free to mark this post as an answer. Otherwise, don't hesitate to respond to this thread if there's anything else that needs to be addressed.
Kind Regards,
Crest_Z