How to I reset ?

[Amer7]

Hello,
My calculator was working fine, but from some strange reason its giving me wrong derivative results in CAS.

For example     - this is correct, but when i type the same example in my calculator it returns 0.

I have tried inserting a paper clip into reset hole but same issue.
- Yes in past I have assigned the values from derivative into d1, d2, a1 and so on. But every I clear them by pressing Vars- then User- and deleting them.

I have also tried going Shift+Mem and clearing CAS, User variable, User but it still returns the wrong derivative answer.


EDIT: For some strange reason when I enter into Spreadsheet app, and Press Home, then CAS it returns the wrong derivative.
But when I enter Function app them press Home, then CAS it gives the correct derivative