you should install the "AutoFull Backup" PlugIn and Schedule it on a weekly or daily Basis maybe at Night at 03.00 AM for Example.
So it's very easy to set your System back into the lastest working Point with flashing via USB Update.
You can use Filezilla to download the Backup File to your PC or NPC over your Home Network.
In your actual Situation there's no Option for you to set up the last working System Point, you've to wait for till the next Update without Bugs will be released.