@Shin-lae-kyaw It looks like the Form 1040X Amended Return became available today Feb. 27 according to the Forms Availability table. IF it's correct, and if it's working.
TurboTax Form Availability Tool
Also, if you are due a Federal refund, it's recommended to wait on the refund to arrive before amending. Or if you owed taxes due, to wait until the return processes.