I’m not surprised this didn’t gain any traction, but here is what I did for anyone who stumbles onto this post.
As I said, all of my files were backed up. I restored the android.jks file from an older backup. Then, I opened a Terminal window and typed in the following:
keytool -storepasswd -new [insert new keystore password] -keystore [insert keystore file name]
keytool -keypasswd -alias [insert alias] -new [insert new key password] -keystore [insert keystore file name]
The keystore and key passwords have to be the same! This fixed my problem, and I hope it helps you too.