From what I've been reading, there is no going back once you get the secure element error. The NFC chip is bricked (for purchases).
The only for sure way to avoid the error is to reset the wallet app before doing any factory resets or flashing of new roms, kernels or radios. The reset has to be done from WITHIN the app, clearing data for the app is not enough.
Secure Element Error Locking Users Out of Google Wallet
The second issue people are having is that provisioning of prepaid cards is still under maintenance.
**scroll down to february 11th**