Hi Michael,,
Apologies, I was rushing out to do something when I saw your post, and I mis-read it.
Unfortunately that means that the (microSD) SD card has become corrupted, and will need to be replaced with a new one, or you can re-flash the existing card to get the B2 working again.
The two options to fix this issue are:
1. Purchase a replacement (micro)SD card from Brennan; the card arrives with the updated B2 software already installed. The price is around £10. You need to state whether your B2 is the early or late model (early models generally pre-2017) have an SD card protruding out of the side of the casing, late models (2017 onwards) have a microSD card inside the case).
OR
2. Re-flash your existing (micro)SD card with the latest software that can be downloaded from the Brennan website (free of charge).
The link to the instructions to do this option are at:
Search down the left hand side of the page for 'New SD Card'
If you want to take this option, I can post additional information which might help to complete this, so just ask!
Let us know what you decide to do..
Regards,
Peter.