I get it was right to call them to check in to see if they needed anything regarding COVID and if they were OK. No answer. No call back. She is a shut in, and she is not away unless she is in the hospital. She always calls back. I feel like she is using this pandemic to inflict even more painful manipulation on me.
Let her. You can't control what she is going to do. You can only control how you respond to it.
You made the call. The ball is now in her court. If she wants to play the silent treatment game, that is her choice. She gets to make that choice, you get to decide how you are going to respond to it.
I like this link about radical acceptance. Once I RA'd my uBPD mom for her true self (and not the mom I wanted her to be), I started to heal and get a sense of control back.
https://bpdfamily.com/message_board/index.php?topic=90041.0